JP6952482B2 - Bottle can caps and how to cap bottle can caps - Google Patents

Description

The present invention relates to a bottle can cap attached to a base portion of a can body of a bottle can , and a method of capping the bottle can cap to the bottle can.

As such a cap for a bottle can, for example, in Patent Document 1, a cap body having a top plate portion and a peripheral wall portion substantially hanging from a peripheral portion of the top plate portion, and a cap main body provided on the inner surface of the top plate portion are arranged. A liner is provided, and the peripheral wall portion is provided with a breakable portion in which a plurality of slit portions extending in the circumferential direction and dented inward in the radial direction are formed in the circumferential direction via a bridge, and the slit portion is provided. A slit is formed that penetrates the peripheral wall portion in the thickness direction, the peripheral wall portion is screwed into the male screw portion formed on the base portion of the bottle can, and the open end portion of the peripheral wall portion is the male screw portion of the bottle can. Described is a bottle can cap that is screwed onto the base of a bottle can by being caught in a bulge that is continuously provided at the lower end in the can axis direction.

In order to manufacture the cap body of such a cap for a bottle can, for example, a rolled plate material made of aluminum or an aluminum alloy is punched into a disk shape, and the outer peripheral portion of the disk shape plate material is sandwiched and supported by a die having circular holes. Then, by inserting a columnar punch into the circular hole, the disk-shaped plate material is narrowed down to form a bottomed cylindrical (cup-shaped) cap body. After that, a slit portion and a bridge are formed on the peripheral wall portion of the cap body.

Here, in Patent Document 1, a disc-shaped plate material having a base plate thickness of 0.21 mm to 0.25 mm and an outer diameter of 65.0 mm to 65.8 mm obtained by punching the rolled plate material is subjected to drawing processing to have a wall thickness of 0. A cap element having a length of .21 mm to 0.30 mm, an outer diameter of 38.2 mm to 38.8 mm, and a length of 17.6 mm to 17.8 mm in the center line direction from the outer surface of the top plate to the open end of the peripheral wall is formed. That is, when the disk-shaped plate material is squeezed and molded into a bottomed cylindrical cap body, the wall thickness of the top plate is almost equal to the original plate thickness, so the wall thickness of the peripheral wall is It is suggested that is equal to or thicker than the original plate thickness.

Further, in the cap body manufactured as described above, after the liner is arranged on the inner surface of the top plate portion, the lower surface of the liner is put on the base portion so as to be brought into contact with the curl portion at the opening end of the base portion. The outer peripheral edge of the top plate is pressed in the can axis direction with a predetermined load and drawn, so that a step portion extending toward the lower end side is formed on the outer peripheral edge toward the outer peripheral side, and the liner becomes a curl portion. Adhere and seal the inside of the can body. Further, by pressing the peripheral wall portion to the inner peripheral side as it is and molding it so as to imitate the male screw portion of the base portion, a female screw portion screwed to the male screw portion is formed, and as described above, the peripheral wall portion is formed. The open end portion is wound around the bulging portion of the base portion, and is attached to the base portion of the can body to be capped.

Japanese Unexamined Patent Publication No. 2006-347600

By the way, in recent years, for the purpose of resource saving and energy saving by reducing the weight of bottle cans, it has been required to reduce the original thickness of the plate material such as aluminum formed on the can body of the bottle can. However, when the base plate thickness is thinned in this way to thin the can body of the bottle can, the base plate thickness of the cap body remains thick, and the wall thickness of the top plate portion is almost equal to the base plate thickness as described above. If it is thick, a large load is required for drawing during capping, and the can body whose strength is reduced due to thinning may buckle in the can axial direction. Therefore, it is necessary to thin the cap body of the cap as the can body of the bottle can is thinned.

However, when the thickness of the cap body is thinned in this way, if the wall thickness of the peripheral wall portion of the cap body becomes too thin, the cap body is lifted and deformed and sealed when the internal pressure becomes high in a beverage can or the like under internal pressure. The property is impaired, and when the bottle can is dropped, leakage may occur, and in some cases, the cap body may come off from the can body. On the other hand, based on the suggestion described in Patent Document 1, from a disk-shaped plate material to a bottomed cylindrical shape so that the wall thickness of the peripheral wall portion is equal to or thicker than the original plate thickness. When the cap body is drawn, the load in the radial direction on the can shaft becomes large especially when the female thread portion is formed during capping, and the base portion may be deformed in this radial direction.

The present invention has been made under such a background, and even when the cap body is thinned due to the thinning of the can body of the bottle can, the sealing property is impaired and leaks when the internal pressure becomes high. It is possible to prevent the cap body from coming off from the can body, and it is also possible to prevent the base part from being deformed when forming a female screw part on the peripheral wall part during capping. It is intended a bottle can cap, and to provide a capping method of the cap for the bottle can to a bottle can.

Here, the inventors of the present invention have described the punch insertion direction of the die that supports the outer peripheral portion of the disk-shaped plate material in the die for forming the cap element by drawing the disk-shaped plate material as described above. Regarding the chamfered portion having an arc-shaped cross section formed at the intersection ridge between the upper surface facing the surface and the inner peripheral surface of the circular hole, the radius of the arc is made larger than before, or the radius on the upper surface side is set to the circular hole. When the original plate thickness of the plate material formed on the cap element is thinned by making it larger than the radius of the inner peripheral surface of the cap element, the top plate part on the peripheral wall part of the cap element formed by drawing. It has been found that it is possible to control the wall thickness of this thin-walled portion so as not to be unnecessarily thin while forming a thin-walled portion having a thickness thinner than that of the thin-walled portion.

Therefore, the cap for a bottle can of the present invention has a disk-shaped top plate portion and a disc-shaped top plate portion and the top plate portion in order to solve the above problems and achieve the above-mentioned object based on such findings. It has a cap body that is integrally molded with a peripheral wall portion that extends cylindrically from the outer circumference around the center line of the top plate portion, and is screwed onto a male screw portion formed on the base portion of the can body of a bottle can. A cap for a bottle can, the peripheral wall portion has a female screw forming planned portion on which a female screw is formed at the time of capping, and the female screw forming planned portion is thinner than the top plate portion. A thin portion is formed, and the thinnest portion of the thin portion having the thinnest wall thickness is 92% or more of the wall thickness of the top plate portion.

In the bottle can cap configured as described above, the thin-walled portion of the cap body is formed on the peripheral wall portion of the cap body in which the female screw portion screwed to the male screw portion of the base portion of the can body of the bottle can is formed. Since a thin part that is thinner than the top plate part that is formed from is formed, the female thread part can be formed without increasing the radial load on the center line of the cap body during capping. It is possible to prevent radial deformation of the base portion during capping even with a thin bottle can.

On the other hand, the wall thickness of the thinnest part of this thin part is 92% or more of the wall thickness of the top plate part, the thin part does not become thinner than necessary, and the thin part is sufficient for the peripheral wall part. Since the strength can be ensured, even if the internal pressure becomes high in a beverage can or the like to which the internal pressure is applied, the cap body is lifted and deformed to impair the sealing property and cause leakage, or the cap body is the can body. It is possible to prevent it from coming off from. That is, if the wall thickness of the thinnest portion is less than 92% of the wall thickness of the top plate portion, the female screw portion formed on the peripheral wall portion may be deformed when the internal pressure becomes high.

Here, it is desirable that the thinnest portion is within 10 mm from the top surface of the top plate portion in the direction of the center line. This range is the range in which the female threaded portion is formed on the peripheral wall portion, and if there is the thinnest portion in such a range, a relatively small load is applied in the radial direction with respect to the center line of the cap body and the can shaft of the bottle can. A female screw portion can be formed on the thin-walled portion, and deformation of the base portion during capping can be prevented more reliably.

Further, the capping method of the present invention is a method of capping the cap for a bottle can to such a bottle can, and the top plate portion of the cap body is placed on the top plate portion of the cap body with a load (top load) of 900 N or less to form a base of the can body. It is characterized in that the peripheral wall portion is formed and screwed to the male screw portion while pressing the portion in the direction of the center line. That is, since the cap body can be thinned as described above, the load in the can axis direction (center line direction of the cap body) of drawing processing at the time of capping can be reduced, and the buckling of the can body can be more reliably performed. Can be prevented. Here, if the top load exceeds 900 N, buckling occurs especially in the male screw portion of the base portion of the can body, and the reseal torque when the cap for the bottle can once opened is screwed into the male screw portion to seal it. May increase.

As described above, according to the present invention, even when the cap body is thinned due to the thinning of the can body of the bottle can, the base portion is formed when the female screw portion is formed on the peripheral wall portion during capping. It is possible to prevent deformation from occurring, and when the internal pressure of the can body rises, the cap body is lifted and deformed, resulting in impaired sealing performance and leakage, or the cap body is removed from the can body. You can prevent it from coming off.

It is a partially broken side view which shows one Embodiment of the cap for a bottle can of this invention. X in (a) a cross-sectional view showing an example of (a) an example of a die used when drawing a cap body formed into a cap for a bottle can of the embodiment shown in FIG. 1, and (b) a diagram (a) showing another example. It is an enlarged sectional view of the part corresponding to the part. It is a partially broken part side view which shows one Embodiment of the bottle can of this invention which attached the bottle can cap of the embodiment shown in FIG. 1 to the can body of a bottle can. FIG. 5 is a schematic view of a capping device used in one embodiment of the method of capping a bottle can cap to a bottle can of the present invention in which the bottle can cap of the embodiment shown in FIG. 1 is capped and attached to the can body of the bottle can.

FIG. 1 shows an embodiment of a bottle can cap of the present invention, and FIG. 2 shows a die used for drawing a cap body formed into such a bottle can cap. FIG. 3 shows an embodiment of the bottle can of the present invention to which the bottle can cap is attached, and FIG. 4 shows the bottle can cap of the above embodiment attached to such a bottle can. It shows the capping apparatus used in one Embodiment of the cap cap for a bottle can to a bottle can of this invention in the case of capping.

The cap for a bottle can of the present embodiment includes a bottomed cylindrical cap body 1 formed of a metal material such as aluminum or an aluminum alloy and centered on a center line O, that is, in the cap body 1. The disk-shaped top plate portion 2 and the peripheral wall portion 3 extending cylindrically from the outer periphery of the top plate portion 2 about the center line O are integrally formed. Further, on the back surface (lower surface) 2a of the top plate portion 2, for example, a disk-shaped liner 4 made of a resin mainly made of polyethylene or polypropylene is arranged.

On the peripheral wall portion 3 of the cap body 1, a plurality of knurl recesses 5a are formed on the upper end side near the top plate portion 2 at equal intervals in the circumferential direction, and the knurl 5 is connected to the lower end of the knurl 5. A groove 6 having an outer diameter smaller than the outer diameter of the knurl 5 is formed, and on the lower end side opposite to the top plate portion 2, a bead 7A and a fragile portion 7B are formed on the upper end side. A cylindrical flare (open end) 8 that is connected to the lower end of the fragile portion 7B and extends toward the lower end is formed.

The knurl recess 5a has a slit 5b, which is a vent hole formed in a slit shape in the circumferential direction to release internal pressure at the time of opening, and an upper opening end and a lower opening end of the slit 5b inside the peripheral wall portion 3. It is provided with a protrusion formed by bending toward it. The knurl 5 increases the frictional resistance between the bottle can cap and the finger holding the bottle can cap at the time of opening, so that the bottle can be easily opened without slipping the hand.

Further, in the substantially central portion of the fragile portion 7B in the center line O direction, a plurality of slit portions 7a extending in the circumferential direction and denting inward in the radial direction with respect to the center line O are formed at equal intervals in the circumferential direction. In addition, the portion between these slit portions 7a is a bridge portion 7b. In the slit portion 7a, a slit 7c penetrating the peripheral wall portion 3 is formed on the long side of the slit portion 7a on the upper end side.

Further, the portion between the groove 6 on the upper end side and the bead 7A on the lower end side of the peripheral wall portion 3 is a female screw forming planned portion 9 in which a female screw portion is formed at the time of capping, and this female screw formation. The planned portion 9 has a substantially constant outer diameter, which is larger than the outer diameter of the groove 6 and smaller than the bead 7A. A thin portion 3a having a wall thickness thinner than that of the top plate portion 2 is formed on the peripheral wall portion 3, and the wall thickness of the thinnest portion of the thin wall portion 3a is the top plate portion 2. It is said to be 92% or more of the wall thickness of.

Here, in the present embodiment, the thin-walled portion 3a is formed on the upper end side of the peripheral wall portion 3 near the top plate portion 2, and extends from the top surface (upper surface) 2b of the top plate portion 2 to the lower end of the peripheral wall portion 3. In the cap body 1 having a length of 17.6 mm to 17.8 mm in the center line O direction, the thinnest portion is located within a range of 10 mm from the top surface 2b. Further, the wall thickness of the peripheral wall portion 3 gradually increases from the thinnest portion toward the lower end side of the cap body 1, and the portion of the peripheral wall portion 3 opposite to the thin wall portion 3a on the flare 8 side is , The thick portion 3b is thicker than the top plate portion 2. It is desirable that the maximum value of the wall thickness of the peripheral wall portion 3 in the thick wall portion 3b is about 120% of the wall thickness of the top plate portion 2.

In order to manufacture the cap body 1 of such a bottle can cap, first, a rolled plate material of a metal material such as aluminum or an aluminum alloy is punched into a disk shape, and the outer peripheral portion of the disk-shaped plate material is shown in FIG. It is arranged on the upper surface 10b of a die 10 having a circular hole 10a as shown in a), and is sandwiched and supported between the circular hole 10a and a presser having a circular hole (not shown) having a coaxial circular hole, and is supported by a circular presser. By inserting a cylindrical punch (not shown) into the circular hole 10a of the die 10 from the hole in the punch insertion direction indicated by reference numeral F in the drawing, the disc-shaped plate material is narrowed down to form a bottomed cylindrical cap body. Mold. At this time, at the same time, the open end of the cap body is trimmed to make the height uniform. After that, the cap body 1 is formed by molding the knurl 5, the groove 6, the bead 7A, the fragile portion 7B, the flare 8, and the female screw forming planned portion 9 on the peripheral wall portion of the cap body.

At this time, in the present embodiment, as shown in FIG. 2A, the upper surface 10b of the die 10 facing the punch insertion direction F, that is, the upper surface 10b facing the side opposite to the punch insertion direction F, and the inside of the circular hole 10a. A chamfered portion 10d having an arcuate cross section along the center line of the circular hole 10a is formed on the intersecting ridgeline portion with the peripheral surface 10c, and the radius R of the arc of the chamfered portion 10d is set to, for example, a disk-shaped plate material. It is 0.7 mm to 0.13 mm, preferably 1.0 mm to 1.3 mm, which is larger than the conventional one, with respect to the original plate thickness of 0.235 mm. Alternatively, as shown in FIG. 2B, the arc formed by the cross section of the chamfered portion 10d has a radius A on the upper surface 10b side of the die 10 larger than a radius B on the inner peripheral surface 10c side (for example, the inner circumference). The radius B on the surface 10c side is 0.7 mm to 1.0 mm, and the radius B on the upper surface 10b side is 1.4 mm to 2.0 mm).

Then, the material flowability of the plate material during drawing is improved, and the material is released on the punch insertion direction F side (the portion side that becomes the top plate portion 2) of the peripheral wall portion of the cap body that becomes the peripheral wall portion 3 of the cap body 1. While it is stretched to a larger extent to form a thin wall portion 3a, on the side opposite to the punch insertion direction F (the side where the flare 8 is formed), the wall thickness is thickened and thickened as the wall thickness toward the flare 8 side by drawing. Part 3b is formed, and the wall thickness of each is controlled. The wall thickness of the portion to be the top plate portion 2 is substantially the same as the original plate thickness and is constant.

As shown in FIG. 3, the cap body 1 of the bottle can cap manufactured in this manner is capped and attached to the base portion 12 of the can body 11 of the bottle can filled with the contents such as beverages, and is attached to the market. Will be shipped. Here, the can body 11 of the bottle can is formed in a bottomed cylindrical shape centered on the can shaft C by a metal material such as aluminum or an aluminum alloy like the cap body 1, and has a bottom portion (not shown) and an outer circumference of the bottom portion. The diameter of the cylindrical body 14 centered on the can shaft C is gradually reduced toward the opening 13 on the upper end side (upper side in FIG. 3) of the can body 11, and the diameter is gradually reduced toward the upper end side. It includes a conical base surface-shaped shoulder portion 15, a cylindrical neck portion 16, and the base portion 12.

The base portion 12 has a bulging portion 12a that bulges toward the upper end side and in which the flare 8 of the cap body 1 is wound, a male threaded portion 12b that has been threaded, and the male threaded portion. The uppermost curl portion 12c is formed by folding back the upper end side of 12b to the outer peripheral side and curling it, and then remolding it inward in the radial direction by throttle processing. In such a bottle can, the can body 11 is also thinned, for example, the thickness of the thinnest portion of the wall portion, which is the thin portion on the bottom side of the portion to be the body portion 14, is 0.100 mm to 0.130 mm. The thickness of the flange portion, which is the thick portion on the side opposite to the bottom portion of the body portion 14, is 0.160 mm to 0.210 mm, and the step between the flange portion and the thinnest portion of the wall portion is 0.090 mm or less. It is manufactured by molding the shoulder portion 15, the neck portion 16, and the base portion 12 into the bottomed cylindrical body (DI can), and the column strength (buckling strength with respect to compression in the can axis C direction) is 1500 N or less. NS. That is, the thickness of the flange portion is the thickness of the bottomed cylindrical body before molding the shoulder portion 15, the neck portion 16, and the base portion 12.

The cap body 1 of the bottle can cap of the above embodiment is capped and attached to the base portion 12 of the can body 11 of such a bottle can by a capping device as shown in FIG. This capping device has a bottomed cylindrical pressure block 21 having an open lower end portion capable of advancing and retreating in the can shaft C direction, and a can shaft C direction supported in the pressure block 21 via a spring member 22. A pressure block insert 23 that can be moved forward and backward, and a thread cutting roller 24 and a hem winding roller 25 that are rotatable around their respective axes and are rotatable around the can shaft C and are movable in the radial direction with respect to the can shaft C. And have.

In one embodiment of the method of capping a bottle can cap to a bottle can by such a capping device, the cap body 1 of the bottle can cap covered on the base portion 12 of the bottle can body 11 is As the pressure block 21 arranged coaxially with the center line O of the can shaft C and the cap body 1 descends in the can shaft C direction, the central portion of the top surface 2b of the top plate portion 2 is pressed by the pressure block insert 23. At the same time, the outer peripheral portion of the top plate portion 2 is pressed by the lower end edge of the pressure block 21 to be drawn, and a step portion 2c as shown in FIG. 3 is formed on the outer peripheral portion of the top plate portion 2 to form the liner 4. It is brought into close contact with the curl portion 12c. The load (top load) when the top plate portion 2 of the cap body 1 is pressed against the base portion 12 of the can body 11 is 900 N or less in this embodiment.

Next, while the top plate portion 2 is pressed by the pressure block 21 and the pressure block insert 23 in this way, the thread cutting roller 24 and the hem winding roller 25 are moved to the inner peripheral side in the radial direction with respect to the can shaft C, and the can shaft C is moved. By rotating it around, the flare 8 of the cap body 1 is wound around the lower edge of the bulging portion 12a of the base portion 12 by the hem winding roller 25, and the thread cutting roller 24 is wound along the thread valley portion of the male screw portion 12b. By moving the cap body 1 in a spiral shape, a female screw portion 9a as shown in FIG. 3 is formed on the female screw forming planned portion 9 of the cap body 1. As a result, the cap body 1 is screwed to the base portion 12 to seal the inside of the can body 11, and the bottle can cap is capped and attached to the bottle can.

In the bottle can cap having the above configuration, the female screw is formed on the peripheral wall portion 3 of the cap body 1 in which the female screw portion 9a screwed to the male screw portion 12b of the base portion 12 of the can body 11 of the bottle can is formed. A thin-walled portion 3a having a thickness thinner than that of the top plate portion 2 formed from the thin-walled portion of the cap body is formed in the planned portion 9. Therefore, the female screw portion 9a can be formed on the female screw formation planned portion 9 without increasing the radial load on the center line O of the cap body 1 by the thread cutting roller 24 at the time of capping. Even if the can body 11 of the bottle can is thinned as described above, it is possible to prevent the base portion 12 from being deformed in the radial direction during this capping.

On the other hand, even though the thin-walled portion 3a is said to have a wall thickness of 92% or more of the wall thickness of the top plate portion 2 even at the thinnest portion, the thin-walled portion 3a is thinner than necessary. It will never be. Therefore, since the strength of the peripheral wall portion 3 can be sufficiently maintained even in the thin-walled portion 3a, even if the female screw forming planned portion 9 is formed in the thin-walled portion 3a and the female screw portion 9a is formed by capping. When the internal pressure becomes high in a bottle can such as a beverage can under internal pressure, the cap body 1 is lifted and deformed to impair the sealing property and cause leakage, or the cap body 1 comes off from the can body 11. You can prevent it from happening. That is, if the wall thickness of the thinnest portion is less than 92% of the wall thickness of the top plate portion 2, the female screw portion 9a may be deformed when the internal pressure becomes high.

Further, in the present embodiment, the thinnest portion of the thin portion 3a is located within 10 mm from the top surface 2b of the top plate portion 2 in the center line O direction of the cap body 1. This range is the range in which the female screw forming planned portion 9 in which the female screw portion 9a is formed is formed on the peripheral wall portion 3 as described above, and by arranging the thinnest portion in such a range, the center line O Since the female screw portion 9a can be formed on the thin-walled portion 3a with a relatively small load in the radial direction with respect to the above, it is possible to more reliably prevent the deformation of the base portion 12 in the can body 11 during capping.

Further, in the bottle can having the above configuration in which such a bottle can cap is screwed to the base portion 12, the thickness of the thin portion 3a of the peripheral wall portion 3 in the female screw forming planned portion 9 in which the female screw portion 9a is also formed. Is 92% or more of the wall thickness of the top plate 2, so it is a bottle can for beverage cans under internal pressure, and even if the internal pressure is high, the sealing performance is impaired and leakage occurs, or the cap body It is possible to prevent 1 from coming off from the base portion 12 of the can body 11.

Further, since the bottle can cap having the above configuration can be reliably attached to the can body 11 even if the original plate thickness is reduced, in the drawing process when forming the step portion 2c on the cap body 1 at the time of capping. The load in the center line O direction of the cap body 1 and in the can axis C direction of the can body 11 can be reduced. Therefore, even if the can body 11 is thinned as described above and the column strength of the can body 11 is 1500 N or less as in the bottle can of the present embodiment, buckling is prevented from occurring during this drawing process. Therefore, it is possible to surely promote resource saving and energy saving by reducing the weight of the can body 11.

Similarly, even if the thickness of the base plate of the cap body 1 is reduced in this way, it can be reliably attached to the can body 11. Therefore, in the capping method having the above configuration, as described above, the cap body 1 is stepped on the top plate portion 2. When drawing the portion 2c, the peripheral wall portion 3 can be formed and screwed to the male screw portion 12b while pressing the base portion 12 of the can body 11 in the center line O direction with a load of 900 N or less.

That is, if the top load, which is the load of drawing when molding the step portion 2c during this capping, exceeds 900 N, buckling occurs in the base portion 12, particularly the male screw portion 12b, and the bottle is once opened. The torque (reseal torque) required for screwing the can cap when the can cap is screwed into the male screw portion 12b to seal the can body 11 may increase. However, in the present embodiment, even if the can body 11 is thinned, this torque is increased. Buckling of the can body 11 during drawing can be prevented more reliably, and further resource saving and energy saving can be achieved.

Hereinafter, the effects of the present invention will be demonstrated with reference to examples of the present invention. In this embodiment, based on the above embodiment, a disk-shaped rolled plate material made of an aluminum alloy having a base plate thickness of 0.235 mm has a surface at an intersecting ridge between an upper surface facing the punch insertion direction and a circular hole as described above. By adjusting these radii using a die in which the arc formed by the cross section of the take part is a composite arc in which the radius on the upper surface side is larger than the radius on the inner peripheral surface side, the peripheral wall part is thicker than the top plate part. Three types of bottle cans in which a thin thin portion is formed and the wall thickness of the thinnest portion of the thin portion is controlled to be 92% or more of the wall thickness of the top plate portion. One type of cap was manufactured with 10 pieces, and the remaining 2 types were manufactured with 5 pieces each. Although the disk-shaped rolled plate material is a coating material, a lubricant such as wax is not applied on the coating material during drawing with the die and punch.

Then, for 5 of these bottle can caps and 5 of the remaining 2 types, the load (top load) in the center line O direction in the drawing process during capping is pressed with 850 N. , Capped on the base of the can body of the bottle can. These are referred to as Examples 1 to 3 for each type. Further, as a comparative example with respect to Examples 1 to 3, five pieces having a wall thickness of the thinnest part of the thin part of less than 92% of the wall thickness of the top plate part were manufactured and capped with a top load 850N for comparison. Example 1 was used. Further, five bottle can caps of the same thickness as in Example 1 were capped with a top load of 1000 N to obtain Comparative Example 2.

Then, in Examples 1 to 3 and Comparative Examples 1 and 2, the sealing property of the bottle can by the bottle can cap and the presence or absence of buckling were evaluated. The results are shown in the thickness of the top plate (mm), the thickness of the thinnest part of the thin part (mm), and the ratio of the thickness of the thinnest part to the wall thickness of the top plate (%, in Table 1). It is shown in Table 1 together with the plate thickness ratio) and top load (N). The wall thickness is an average value of 5 bottle can caps of various types. Further, in both Examples 1 to 3 and Comparative Examples 1 and 2, the thinnest portion is located at a position of about 5 mm from the top surface in the center line O direction, and the measurement position in the circumferential direction of the cap body is from the viewpoint of anisotropy in the rolled plate material. The position was set to 90 ° with respect to the rolled grain, which is most easily extended from the ground and thinned.

Further, as the bottle can, a bottle can made of an aluminum alloy for 275 ml (total volume 338 ml) was used, and the column strength of the can body was 1500 N. Then, 275 ml of water was filled in this bottle can, and liquid nitrogen was dropped into the head space portion above the water surface to replace the air and capping was performed. The initial internal pressure of each bottle can ^{is set to 0.1 MPa (1.02 kgf / cm 2} ) at 20 ° C, and the internal pressure after steam pressure deduction at 125 ° C during sterilization is set to 3.65 kgf / cm ^2. , Each bottle can thus capped was subjected to a retort treatment at 121 ° C.-20 minutes.

To evaluate the sealing performance, a bottle can that has been left for one day after retort treatment is dropped on an iron plate that is tilted 10 ° from a height of 30 cm in an inverted (vertical) position, and then placed upright and left for one day. If the internal pressure before and after the drop is measured and drops by 30 kPa or more, a leak occurs, and if even one of the 5 bottle cans with 5 bottle can caps is leaked, it fails. (Cross mark), and pass (circle mark) when no leakage occurred.

Furthermore, regarding the presence or absence of buckling, after opening the bottle can once, return it to 30 ° in front of the original position and measure the maximum torque required when resealing, and the maximum torque is 10 Ncm or more. If there is even one bottle can, it is considered that the male screw part of the mouthpiece has buckled and it is rejected (cross mark), and if the maximum torque of all five cans is less than 10 Ncm, it is buckled. Passed (circled) as if there was no.

From the results in Table 1, first, in Comparative Example 1 in which the plate thickness ratio, which is the ratio of the wall thickness of the thinnest part to the wall thickness of the top plate part, is 89%, which is less than 92%, the thin part is too thin. There was a bottle can in which the female screw part was deformed by the internal pressure and a drop leak occurred, and the sealing property was impaired. Further, in Comparative Example 2 in which the top load, which is the load in the center line O direction in the drawing process during capping, was 1000N, which is larger than 900N, the male screw portion was buckled and deformed during capping, resulting in the female screw. In some cases, the friction with the part became large, and the maximum torque required for resealing was 10 N · cm or more. In contrast to Comparative Examples 1 and 2, in Examples 1 to 3, leakage did not occur due to deformation of the female screw portion even when the internal pressure in the can body became high, and the maximum torque required for resealing was 10 N. It was less than cm and no buckling was observed.

1 Cap body 2 Top plate part 3 Peripheral wall part 3a Thin wall part 3b Thick part 9 Female screw formation planned part 9a Female screw part 10 Die 11 Can body 12 Base part 12a Swelling part 12b Male screw part 12c Curl part O Cap body 1 Center line C can shaft

Claims (3)

It is provided with a cap body in which a disk-shaped top plate portion and a peripheral wall portion extending cylindrically from the outer periphery of the top plate portion about the center line of the top plate portion are integrally formed. A bottle can cap that is screwed onto the male thread formed on the base.
The peripheral wall portion has a female screw forming planned portion in which a female screw is formed at the time of capping, and a thin-walled portion thinner than the top plate portion is formed in the female screw forming planned portion.
A cap for a bottle can, wherein the thinnest portion of the thin portion has a wall thickness of 92% or more of the wall thickness of the top plate portion. The cap for a bottle can according to claim 1, wherein the thinnest portion is within a range of 10 mm or less from the top surface of the top plate portion in the direction of the center line. A method for capping a bottle can cap into a bottle can, wherein the bottle can cap according to claim 1 or 2 is screwed onto a male screw portion formed on a base portion of the can body of the bottle can.
A bottle characterized in that the top plate portion of the cap body is pressed against the base portion of the can body with a load of 900 N or less in the direction of the center line, the peripheral wall portion is molded, and the bottle is screwed to the male screw portion. How to cap a bottle can cap on a can.

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