JP2018131262A - Cap for bottle can, bottle can, and method of capping bottle can with cap for bottle can - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage from being caused and also prevent a cap body from falling from a can body of a bottle can in spite of a rise in internal pressure even when the cap body is made thinner as the can body is made thinner, and to prevent a mouthpiece part from deforming when a female screw part is formed at a peripheral wall part in capping.SOLUTION: A cap for a bottle can comprises a cap body 1 having a disk-like top plate part 2 and a peripheral wall part 3 molded in one body, the peripheral wall part 3 extending cylindrically from an outer periphery of the top plate part 2 about a center line O of the top plate part 2 in the center. The cap for a bottle can is threadably engaged with a male screw part formed at a mouthpiece part of a can body of a bottle can. A thin part 3a which is less in thickness than the top plate part 2 is formed at the peripheral wall part 3, and a thickness of the thinnest part, which is thinnest, of the thin part 3a is 92% or larger than the thickness of the top plate part 2.SELECTED DRAWING: Figure 1

Description

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

  As such a bottle can cap, for example, in Patent Document 1, a cap body including a top plate portion and a peripheral wall portion substantially hanging from a peripheral portion of the top plate portion, and an inner surface of the top plate portion are disposed. The peripheral wall portion is provided with an easily breakable portion in which a plurality of slit portions extending in the circumferential direction and recessed inward in the radial direction are formed in the circumferential direction via a bridge. A slit that penetrates the peripheral wall portion in the thickness direction is formed, and the peripheral wall portion is threadedly engaged with the male screw portion formed on the mouthpiece portion of the bottle can, and the open end of the peripheral wall portion is connected to the male screw portion of the bottle can. There is described a bottle can cap that is screwed into a cap portion of a bottle can by being wound around a bulging portion that is continuously provided at the lower end in the can axis direction.

  In order to manufacture the cap body of such a bottle can cap, 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 plate material is sandwiched and supported by a die having a circular hole. Then, by inserting a cylindrical punch into the circular hole, the disk-shaped plate material is squeezed to form a bottomed cylindrical (cup-shaped) cap body. Thereafter, slits and bridges are formed in the peripheral wall portion of the cap body.

  Here, in Patent Document 1, a plate-shaped plate material having a thickness of 0.21 mm to 0.25 mm and an outer diameter of 65.0 mm to 65.8 mm punched from the rolled plate material is subjected to a drawing process to obtain a wall thickness of 0. .21 mm to 0.30 mm, outer diameter 38.2 mm to 38.8 mm, and a cap body having a length in the center line direction from the outer surface of the top plate portion to the open end of the peripheral wall portion is formed. That is, when the disk-shaped plate material is drawn to form a bottomed cylindrical cap body, the thickness of the top plate portion is substantially equal to the original plate thickness. It is suggested that is equal to the original plate thickness or thicker than the original plate thickness.

  In addition, the cap body manufactured as described above has a liner disposed on the inner surface of the top plate portion, and then covers the base portion so that the lower surface of the liner is brought into contact with the curled portion of the mouth portion opening end. The outer peripheral edge of the top plate portion is pressed in the can axis direction with a predetermined load and drawn to form a stepped portion on the outer peripheral edge toward the outer peripheral side, and the liner becomes the curled portion. Adheres closely and seals inside the can body. Furthermore, by pressing the peripheral wall portion to the inner peripheral side as it is and forming so as to follow the male screw portion of the base portion, a female screw portion that is screwed into the male screw portion is formed, and as described above, the peripheral wall portion The open end portion is wound around the bulging portion of the base portion, attached to the base portion of the can body, and capped.

JP 2006-347600 A

  By the way, in recent years, for the purpose of resource saving and energy saving by reducing the weight of the bottle can, it has been required to reduce the thickness of the original plate of aluminum or the like formed on the can body of the bottle can. However, when the original plate thickness is reduced to make the bottle body thinner, the original plate thickness of the cap body remains thick, and the thickness of the top plate portion is substantially equal to the original plate thickness as described above. If it is thick, a large load is required in the drawing process at the time of capping, and there is a risk that buckling in the can axis direction may occur in the can body whose strength has been reduced by thinning. Therefore, it is necessary to reduce the thickness of the cap body of the cap as the thickness of the can body of the bottle can decreases.

  However, when 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 will be lifted and deformed and sealed when the internal pressure increases in beverage cans and the like where internal pressure is applied. If the bottle can is dropped, leakage may occur, or the cap body may come off from the can body in some cases. On the other hand, based on the suggestion described in Patent Document 1, the bottomed cylindrical shape is formed from a disk-shaped plate material so that the thickness of the peripheral wall portion is equal to or thicker than the original plate thickness. When the cap body is drawn, the radial load on the can shaft when the internal thread portion is formed particularly during capping increases, and there is a risk that the base portion is deformed in the radial direction.

  The present invention has been made under such a background, and even when the cap body is thinned with the thinning of the can body of the bottle can, when the internal pressure becomes high, the sealing performance is impaired and leakage occurs. It is possible to prevent the cap body from being detached from the can body and to prevent the cap part from being deformed when the female thread part is formed on the peripheral wall part during capping. Caps for bottle cans, bottle cans in which such caps for bottle cans are screwed into male screw portions formed in a cap part of a can body, and a method for capping the bottle can caps onto the bottle cans The purpose is that.

  Here, the inventors of the present invention, as described above, in the die when drawing the disk-shaped plate material to form the cap body, the die punch insertion direction of the die that supports the outer peripheral portion of the disk-shaped plate material For the chamfered portion having a circular arc cross section formed at the intersecting ridgeline portion between the upper surface facing the inner surface and the inner peripheral surface of the circular hole, the radius of the circular arc is made larger than before, or the radius on the upper surface side is a circular hole If the original plate thickness of the plate material formed on the cap body is reduced by making it larger than the radius of the inner peripheral surface of the cap body, the top plate portion is formed on the peripheral wall portion of the cap body formed by drawing. As a result, the inventors have found that it is possible to control the thickness of the thin portion so as not to be unnecessarily thin while forming a thin portion having a thinner thickness.

  Therefore, the cap for the bottle can of the present invention is based on such knowledge, and in order to solve the above-described problems and achieve the above-described object, the disk-shaped top plate portion and the top plate portion A cap body integrally formed with a peripheral wall portion extending in a cylindrical shape from the outer periphery around the center line of the top plate portion is provided, and is screwed to a male screw portion formed in a cap portion of a can body of a bottle can. A cap for a bottle can, wherein the peripheral wall portion is formed with a thin portion thinner than the top plate portion, and the thickness of the thinnest portion of the thin portion where the thickness is the thinnest is, It is characterized by being 92% or more of the thickness of the top plate portion.

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

  On the other hand, the thickness of the thinnest part is 92% or more of the thickness of the top plate part, and the thin part does not become unnecessarily thin. Since the strength can be secured, even when the internal pressure is high in beverage cans, etc. where internal pressure is applied, the cap main body is lifted and deformed, resulting in loss of sealing performance and leakage, or the cap main body can be It can be prevented from coming off. That is, if the thickness of the thinnest portion is less than 92% of the thickness of the top plate portion, the internal thread portion formed on the peripheral wall portion may be deformed when the internal pressure increases.

  Here, it is desirable that the thinnest portion is within a range of 10 mm or less from the top surface of the top plate portion in the center line direction. This range is a range in which the female thread portion is formed on the peripheral wall portion, and if there is a 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 axis of the bottle can. An internal thread part can be shape | molded in a thin part, and it becomes possible to prevent more reliably the deformation | transformation of a nozzle | cap | die part at the time of capping.

  Further, the bottle can of the present invention is characterized in that such a bottle can cap is screwed to a male screw portion formed in a cap portion of the can body, as described above. It is a beverage can etc. to which the internal pressure is applied, and even if the internal pressure increases, the cap body can be prevented from coming off from the base part of the can body. Here, in the bottle can cap of the present invention, it can be securely attached to the can body even if the original plate thickness is reduced as described above. The load can be reduced. For this reason, the can body may be thinned, and the column strength of the can body may be 1500 N or less.

  Furthermore, the capping method of the present invention is a method of capping the bottle can cap into such a bottle can, wherein the top plate portion of the cap body is subjected to a cap (top load) of 900 N or less and the cap body of the can body. The peripheral wall portion is molded and screwed to the male screw portion while pressing the portion in the center line direction. 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) during drawing can be reduced, and the can body can be more reliably buckled. Can be prevented. Here, when the top load exceeds 900 N, the male screw part of the can body, in particular, the male screw part buckles, and the reseal torque when the bottle cap once opened is screwed into the male screw part and sealed. May increase.

  As described above, according to the present invention, even when the cap body is thinned with the thinning of the can body of the bottle can, the cap portion is formed when the female thread portion is formed on the peripheral wall portion during capping. It becomes possible to prevent the deformation from occurring, and when the internal pressure of the can body increases, the cap body lifts and deforms so that the sealing performance is lost and leakage occurs. It can be prevented from coming off.

It is a partially broken side view which shows one Embodiment of the cap for bottle cans of this invention. FIG. 1A is a cross-sectional view showing an example of a die used for drawing a cap body formed on the bottle can cap of the embodiment shown in FIG. 1, and FIG. It is an expanded sectional view of the part equivalent to a part. It is a partially broken partial side view which shows one Embodiment of the bottle can of this invention which attached the cap for bottle cans of embodiment shown in FIG. 1 to the can main body of a bottle can. It is the schematic of the capping apparatus used for one Embodiment of the capping method of the bottle can cap to the bottle can of this invention attached by capping the bottle can cap of embodiment shown in FIG. 1 to the can main body of a bottle can.

  FIG. 1 shows an embodiment of a bottle can cap according to the present invention, and FIG. 2 shows a die used for drawing a cap body formed in 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. FIG. 4 shows the bottle can cap of the above embodiment on such a bottle can. The capping apparatus used for one Embodiment of the capping method of the cap for bottle cans to the bottle can of this invention in the case of capping is shown.

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

  On the peripheral wall 3 of the cap body 1, a plurality of knurl recesses 5 a are formed at equal intervals in the circumferential direction on the upper end side near the top plate portion 2, and are 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 a bead 7A and an easily breakable portion 7B are provided on the upper end side on the lower end side opposite to the top plate portion 2, A cylindrical flare (open end portion) 8 extending to the lower end side and extending to the lower end of the easily breakable portion 7B is formed.

  The knurled recess 5a has a slit 5b that is a vent hole that is formed in a slit shape in the circumferential direction to release the internal pressure when the cap is opened, and an upper opening end and a lower opening end of the slit 5b on the inner side of the peripheral wall 3 And a projecting portion formed by bending toward it. The knurl 5 increases the frictional resistance between the bottle can cap and the finger gripping the cap at the time of opening, and can be easily opened without sliding the hand.

  Also, a plurality of slit portions 7a extending in the circumferential direction in a side view and recessed inward in the radial direction with respect to the center line O are formed at equal intervals in the circumferential direction at a substantially central portion in the center line O direction of the easily breakable portion 7B. In addition, a portion between the 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 on the upper end side of the slit portion 7a.

  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 formation scheduled portion 9 in which a female screw portion is formed at the time of capping. The planned portion 9 has a substantially constant outer diameter that is larger than the outer diameter of the groove 6 and smaller than the bead 7A. And the thin wall part 3a whose thickness is thinner than the top-plate part 2 is formed in the surrounding wall part 3, The thickness of the thinnest part where thickness is the thinnest among this thin-wall part 3a is the top-plate part 2 It is said to be 92% or more of the wall thickness.

  Here, in this embodiment, the thin part 3a is formed in the upper end part near the top-plate part 2 among the surrounding wall parts 3, From the top | upper surface (upper surface) 2b of the top-plate part 2 to the lower end of the surrounding wall part 3 In the cap body 1 having a length in the direction of the center line O of 17.6 mm to 17.8 mm, the thinnest part is located within a range of 10 mm from the top surface 2b. Furthermore, the thickness of the peripheral wall portion 3 gradually increases from the thinnest portion toward the lower end portion of the cap body 1, and the portion on the flare 8 side of the peripheral wall portion 3 opposite to the thin portion 3a is The thick portion 3b is made thicker than the top plate portion 2. In addition, 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 such a cap body 1 for a bottle can cap, first, the rolled plate material of the metal material such as aluminum or aluminum alloy is punched into a disk shape, and the outer peripheral portion of the disk-shaped plate material is shown in FIG. a) is disposed on the upper surface 10b of the die 10 having the circular hole 10a as shown in FIG. 5a, and is sandwiched and supported between the circular hole 10a and a presser (not shown) having a coaxial circular hole, and the presser is circular. By inserting a cylindrical punch (not shown) from the hole into the circular hole 10a of the die 10 in the punch insertion direction indicated by the symbol F in the drawing, the disk-like plate material is narrowed down to form a bottomed cylindrical cap body. Mold. At this time, the open end portion of the cap body is trimmed at the same time so as to have the same height. Thereafter, the knur 5, the groove 6, the bead 7 </ b> A, the breakable portion 7 </ b> B, the flare 8, and the female screw formation scheduled portion 9 are formed on the peripheral wall portion of the cap body to form the cap body 1.

  At this time, in this 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 away from the punch insertion direction F, and the circular hole 10a A chamfered portion 10d in which a cross section along the center line of the circular hole 10a forms an arc shape is formed at the intersecting ridgeline portion with the peripheral surface 10c, and the radius R of the arc of the chamfered portion 10d is defined as, for example, a disk-shaped plate The original plate thickness of 0.235 mm is 0.7 mm to 0.13 mm, preferably 1.0 mm to 1.3 mm, which is larger than the conventional thickness. Alternatively, as shown in FIG. 2B, an arc formed by the cross section of the chamfered portion 10d is set such that the radius A on the upper surface 10b side of the die 10 is larger than the 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 at the time of drawing processing is improved, and the material is present on the punch insertion direction F side (part 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. On the other side of the punch insertion direction F (on the side that becomes the flare 8), the thickness is increased by drawing and becomes thicker toward the flare 8 side. The part 3b is formed, and the thickness of each is controlled. In addition, the thickness of the part used as the top-plate part 2 is constant, substantially unchanged from the original board thickness.

  The cap body 1 of the bottle can cap manufactured in this way is capped and attached to the base portion 12 of the can body 11 of the bottle can filled with contents such as beverage as shown in FIG. Shipped. Here, the can body 11 of the bottle can is formed in a cylindrical shape with a bottom centered on the can axis C by a metal material such as aluminum or an aluminum alloy in the same manner as the cap body 1, and includes a bottom portion (not shown) and an outer periphery of the bottom portion. The diameter of the can body 11 gradually decreases toward the opening 13 on the upper end side (upper side in FIG. 3) of the can body 11 and the cylindrical body portion 14 centering on the can axis C with a constant inclination toward the upper end side. A frustoconical shoulder 15, a cylindrical neck 16, and the base 12 are provided.

  The base portion 12 is further swelled in order toward the upper end side in order toward the outer peripheral side, the bulging portion 12a into which the flare 8 of the cap body 1 is wound, a threaded male screw portion 12b, and the male screw portion. An uppermost curled portion 12c is formed which is curled by folding the upper end side toward the outer peripheral side from 12b and then being reshaped radially inward by throttle processing. In such a bottle can, the can main body 11 is also thinned. For example, the thickness of the thinnest part of the wall part which is the thin part on the bottom side of the part to become the body part 14 is 0.100 mm to 0.130 mm. The thickness of the flange portion which is the thick portion of the portion 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 15, neck 16 and base 12 on the bottomed cylindrical body (DI can), and the column strength (buckling strength against compression in the can axis C direction) is 1500 N or less. The That is, the thickness of the flange portion is the thickness of the bottomed cylindrical body before the shoulder portion 15, the neck portion 16, and the base portion 12 are formed.

  The cap body 1 of the bottle can cap of the above embodiment is attached to the base 12 of the can body 11 of the bottle can by being capped by a capping device as shown in FIG. The capping device has a bottomed cylindrical pressure block 21 that is capable of advancing and retreating in the direction of the can axis C and having an open lower end, and a can axis C direction that is 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 threading roller 24 and a skirt winding roller 25 that are rotatable about their respective axes, are rotatable about the can axis C, and are movable in the radial direction with respect to the can axis C. And.

  In one embodiment of the method for capping a bottle can cap into the bottle can of the present invention by using such a capping device, the cap body 1 of the bottle can cap that covers the base 12 in the can body 11 of the bottle can is: When the pressure block 21 arranged coaxially with the can axis C and the center line O of the cap body 1 is lowered in the direction of the can axis C, the central portion of the top surface 2b of the top plate portion 2 is pressed by the pressure block insert 23. In addition, the outer peripheral portion of the top plate portion 2 is pressed by the lower edge of the pressure block 21 and drawn, and a step portion 2c as shown in FIG. It is brought into close contact with the curled portion 12c. In addition, the load (top load) when pressing the top plate part 2 of the cap body 1 against the base part 12 of the can body 11 is set to 900 N or less in this embodiment.

  Next, the can shaft C is moved while moving the threading roller 24 and the skirt winding roller 25 toward the radially inner side with respect to the can shaft C while the top plate portion 2 is pressed by the pressure block 21 and the pressure block insert 23 in this way. The flare 8 of the cap body 1 is wound around the lower edge portion of the bulging portion 12a of the base portion 12 by the bottom winding roller 25, and the threading roller 24 is moved along the thread valley portion of the male screw portion 12b. Then, the internal thread portion 9a as shown in FIG. 3 is formed in the internal thread formation scheduled portion 9 of the cap body 1 by moving the spiral body. Thereby, the cap main body 1 is screwed to the base part 12 to seal the inside of the can main body 11, and the bottle can cap is capped and attached to the bottle can.

  In the bottle can cap having the above-described configuration, the internal thread formation in the peripheral wall portion 3 of the cap body 1 in which the internal thread portion 9a to be screwed to the external thread portion 12b of the cap portion 12 in the can body 11 of the bottle can is thus formed. A thin portion 3 a having a thickness smaller than that of the top plate portion 2 formed from the thin portion of the cap element body is formed in the planned portion 9. For this reason, the internal thread portion 9a can be formed on the internal thread 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 during capping. Thus, even if the can body 11 of the bottle can is thinned, it is possible to prevent the radial deformation of the base portion 12 during the capping.

  On the other hand, even though it is the thin portion 3a, the thin portion 3a has a thickness of 92% or more of the thickness of the top plate portion 2 even at the thinnest portion, and the thin portion 3a is thinner than necessary. Never become. Accordingly, since the strength of the peripheral wall portion 3 can be sufficiently maintained even in the thin wall portion 3a, even if the female screw formation scheduled portion 9 is formed in the thin wall portion 3a and the female screw portion 9a is formed by capping. When the internal pressure is increased in a bottle can such as a beverage can that has been subjected to internal pressure, the cap body 1 is lifted and deformed, resulting in loss of sealing performance and leakage, or the cap body 1 coming off the can body 11 Can be prevented. That is, if the thickness of the thinnest portion is less than 92% of the thickness of the top plate portion 2, there is a possibility that the internal thread portion 9a is deformed when the internal pressure is increased.

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

  Furthermore, in the bottle can having the above-described configuration in which such a bottle can cap is screwed onto the base portion 12, the thickness of the thin wall portion 3a of the peripheral wall portion 3 in the female screw formation scheduled portion 9 where the female screw portion 9a is also formed. Is a bottle can etc. for beverage cans with internal pressure applied, and even if the internal pressure increases, the sealing performance will be impaired and leakage will occur. 1 can be prevented from coming off from the base part 12 of the can body 11.

  In the bottle can cap having the above-described configuration, even if the original plate thickness is reduced, the cap can be securely attached to the can main body 11. Therefore, in the drawing process when the step portion 2c is formed on the cap main body 1 at the time of capping. The load in the direction of the center line O of the cap body 1 and the direction of the can axis C of the can body 11 can be reduced. For this reason, 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 the drawing process. Therefore, the can main body 11 can also promote resource saving and energy saving by reliably reducing the weight.

  Similarly, the cap body 1 can be securely attached to the can body 11 even if the original thickness of the cap body 1 is reduced in this way. Therefore, in the capping method having the above configuration, the top plate portion 2 of the cap body 1 is stepped as described above. When the portion 2c is drawn, 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 direction of the center line O with a load of 900 N or less.

  That is, when the top load, which is a drawing load when forming the stepped portion 2c during capping, exceeds 900 N, the male screw portion 12b of the base portion 12 is particularly buckled and deformed, and once opened. Although the torque required for screwing when sealing the can body 11 by screwing the can cap into the male threaded portion 12b (reseal torque) may increase, even if the can body 11 is made thinner, Buckling of the can body 11 at the time of drawing can be more reliably prevented, and further resource and energy savings can be achieved.

  Examples of the present invention will be given below to demonstrate the effects of the present invention. In this example, based on the above embodiment, a disk-shaped rolled sheet material made of an aluminum alloy having a base plate thickness of 0.235 mm has a surface at the intersecting ridge line portion between the upper surface facing the punch insertion direction and the circular hole as described above. Using a die that is a composite arc in which the radius of the upper surface side is larger than the radius of the inner peripheral surface side, the arc formed by the cross section of the handle is adjusted, and the peripheral wall portion is made thicker than the top plate portion. Three types of bottle cans that are formed so that a thin thin part is formed and the thickness of the thinnest part of the thin part is the thinnest part becomes 92% or more of the thickness of the top plate part Ten types of caps were manufactured for one type and five for the remaining two types. The disk-shaped rolled plate material is a coating material, but a lubricant such as wax is not applied on the coating material at the time of drawing with the die and the punch.

  For these bottle can caps, about 5 out of 1 type and the remaining 2 types of 5 caps, the load in the center line O direction (top load) in the drawing process at the time of capping is pressed at 850N. Then, it was capped on the base of the can body of the bottle can. These are referred to as Examples 1 to 3 for each type. In addition, as a comparative example for Examples 1 to 3, five of the thinnest part having a thickness of less than 92% of the thickness of the top plate part were produced and capped with a top load 850N for comparison. Example 1 was adopted. Further, Comparative Example 2 was prepared by capping 5 bottle caps of one kind having the same wall thickness as in Example 1 with Top Load 1000N.

  In Examples 1 to 3 and Comparative Examples 1 and 2, the sealing performance of the bottle can by the bottle can cap and the presence or absence of buckling were evaluated. The results are shown as the thickness of the top plate (mm), the thickness of the thinnest portion (mm), and the ratio of the thickness of the thinnest portion to the thickness of the top plate (%, in Table 1) Table 1 together with the top load (N). The wall thickness is an average value of five bottle caps. The thinnest part of each of Examples 1 to 3 and Comparative Examples 1 and 2 is located at a position of about 5 mm in the direction of the center line O from the top surface, and the measurement position in the circumferential direction of the cap body is a viewpoint of anisotropy in the rolled sheet material. And 90 ° with respect to the rolling line that is most likely to extend from the roll.

Further, a bottle can made of an aluminum alloy for 275 ml (total amount: 338 ml) was used as the bottle can, and the column strength of the can body was 1500 N. Then, 275 ml of water was filled in the 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 deducting the vapor pressure at 125 ° C. during sterilization is set to 3.65 kgf / cm ^2. Each bottle can capped in this way was subjected to a retort treatment at 121 ° C. for 20 minutes.

  In addition, the evaluation of sealing performance was carried out by dropping a bottle can left for 1 day after retorting on an iron plate tilted 10 ° from a height of 30 cm in an inverted (vertical) position, and then leaving it in a straight position for 1 day. If the internal pressure before and after the drop is measured and the pressure drops by 30 kPa or more, if a leak occurs, it will be rejected if any one of the 5 bottle cans with 5 bottle can caps attached leaks. The case where no leakage occurred was defined as a pass (circle).

  Furthermore, for the presence or absence of buckling, after opening the bottle can once, measure the maximum torque required when resealing by returning to 30 ° before the original position, the maximum torque is 10N · cm or more The case where there is at least one bottle can is rejected as a result of buckling of the male screw part of the base part (cross mark), and the case where the maximum torque of all 5 cans is less than 10 N · cm. It was set as a pass (circle) as what does not have.

  From the results of Table 1, first, in Comparative Example 1 in which the thickness ratio, which is the ratio of the thickness of the thinnest portion to the thickness of the top plate portion, is 89% which is less than 92%, the thin portion is too thin. There is a bottle can in which the internal thread portion is deformed by internal pressure to cause a drop leak, and the sealing performance is impaired. Further, in Comparative Example 2 in which the top load, which is the load in the direction of the center line O in the drawing process at the time of capping, is 1000 N, which is larger than 900 N, as a result of deformation due to buckling of the male screw portion during capping, the female screw In some cases, the maximum torque required for resealing was 10 N · cm or more. In contrast to these Comparative Examples 1 and 2, in Examples 1 to 3, there was no leakage due to deformation of the female thread portion even when the internal pressure in the can body was high, and the maximum torque required for resealing was 10 N · It was less than cm and no buckling was observed.

DESCRIPTION OF SYMBOLS 1 Cap main body 2 Top plate part 3 Peripheral wall part 3a Thin part 3b Thick part 9 Female thread formation scheduled part 9a Female thread part 10 Die 11 Can main body 12 Cap part 12a Protruding part 12b Male screw part 12c Curl part O Cap main body 1 Center line C can axis

Claims (5)

A cap body in which a disk-shaped top plate portion and a peripheral wall portion extending in a cylindrical shape around the center line of the top plate portion from the outer periphery of the top plate portion are integrally formed, A cap for a bottle can screwed into a male screw portion formed in a base portion,
In the peripheral wall part, a thin part thinner than the top plate part is formed,
A bottle can cap characterized in that the thickness of the thinnest portion of the thinned portion is 92% or more of the thickness of the top plate portion.   The said thinnest part exists in the range within 10 mm from the top | upper surface of the said top-plate part in the said centerline direction, The cap for bottle cans of Claim 1 characterized by the above-mentioned.   A bottle can according to claim 1 or 2, wherein the bottle can cap is screwed into a male screw portion formed in a base portion of the can body.   The bottle can according to claim 3, wherein the column strength of the can body is 1500 N or less. A method for capping a bottle can cap into a bottle can according to claim 3 or 4,
The peripheral wall portion is formed and screwed to the male screw portion while pressing the top plate portion of the cap body to the base portion of the can body with a load of 900 N or less in the center line direction. A method for capping bottle caps into cans.

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