JP2004238071A - Can lid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent blowoff in which much content is dispersed around all at once from happening with the break of a caulking part following buckling caused by an abnormal can inner pressure rise as to a can lid for a positive inner pressure can with a high inner pressure. <P>SOLUTION: This can lid comprises, as one continuous body, a reinforcement annular groove 3 recessed in the inside of a can to the out side from the circumference of a disk-like panel 2, an inclining chuck wall part 4 continuing to the outside wall of the groove 3, and a flange curl part 5 whose outer periphery is curled on the outer periphery of a roughly disk shaped panel part 2. An easily deformable buckling triggering part 6 permitting easy deformation for forming an angle acting as an initiation point of buckling is formed near the periphery of the panel 2. A score line 7 to be broken by buckling deformation is formed near the triggering part 6. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can lid (an upper lid or a bottom lid) fixed to an opening end of a can body as an end plate portion of a can container by double winding, and in particular, a positive internal pressure can (positive pressure can) having a high internal pressure of the can. The present invention relates to a can lid structure which does not cause blow-off due to breakage of a tightened portion even if buckling occurs due to abnormal rise in internal pressure of the can.
[0002]
[Prior art]
In cans of positive internal pressure cans (positive pressure cans) with high internal pressure, such as beverage cans containing sparkling beverages such as carbonated beverages and beer, the internal pressure of the can increased abnormally due to vibration, impact, temperature rise, etc. Occasionally, the so-called buckling phenomenon occurs in which the peripheral portion of the can lid wound around the can body is inverted and the panel portion is angularly deformed to the outside of the can, so-called buckling has occurred. After that, if the internal pressure of the can continues to rise and becomes abnormally high, it will be pulled by the cornering part, and the can lid side (cover hook) and can body side (body hook) of the tightening part following the chuck wall part The so-called blow-off in which a large amount of contents are scattered around at once or the can lid is blown off because the engagement state is elongated, and finally the tightened portion is broken and the can lid comes off from the can body. A phenomenon called
[0003]
Regarding the fact that the can lid comes off due to such an increase in the internal pressure of the can, for example, Japanese Patent Publication No. 51-31606 discloses that "a cylindrical metal cylinder with a bottom lid is double-rolled and the resistance to the internal pressure of the container is reduced. In a hermetically sealed internal pressure vessel provided with a dome-shaped metal upper lid having a resistance smaller than that of the bottom lid, a portion including an upper end of a double tightening portion of the dome-shaped metal upper lid and the metal body is provided with the upper lid. A large number of score lines are provided in the diametric direction of the aerosol container "with a pressure release mechanism. When the internal pressure increases due to high heat by such a pressure release mechanism, it is described. It describes that the bottom lid is prevented from being blown off by the internal pressure by breaking the score line by bulging the dome-shaped metal top lid and discharging the contents from the leak hole thereby.
[0004]
[Problems to be solved by the invention]
By the way, the pressure release mechanism of the conventional well-known sealed internal pressure container as described above relates to an aerosol container provided with a dome-shaped metal lid, and a score line is formed in accordance with the swelling of the metal lid due to an increase in internal pressure. By breaking the (score line), the bottom lid is prevented from blowing off due to the internal pressure. However, when the dome-shaped metal top lid swells due to an increase in the internal pressure, the buckling of the beverage can in the buckling. It is not known at which point of the metal upper lid such a cornering deformation occurs (it is not described in the above cited publication that deformation such as cornering deformation occurs). The metal upper lid is provided with a large number of diametrical notching lines at intervals in the circumferential direction at a portion including the upper end of the double clinching portion.
[0005]
Therefore, in a beverage can of a positive internal pressure can (positive pressure can) having a high internal pressure, it is possible to prevent the occurrence of blow-off due to the breakage of the tightened portion after the inside of the can has abnormally risen and buckling has occurred. For this reason, if a conventionally known pressure release mechanism as described above is applied, by providing a large number of score lines (cut lines) on the can lid, the strength of the can lid itself is greatly reduced, and the internal pressure of the can is reduced. Even if the increase is not so large, the score line breaks, or the score line breaks only by receiving a drop impact, so that the score line is broken even at high internal pressures such as when buckling occurs. There is a problem that an object may be released.
[0006]
The present invention has been made to solve the above problems, and specifically, a can lid for a positive internal pressure can having a high internal pressure of the can, and the buckling occurred due to an abnormal increase in the internal pressure of the can. It is an object of the present invention to prevent a blow-off in which a large amount of contents are scattered around at once due to the destruction of the tightening portion.
[0007]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION In order to solve the above-described problems, the present invention extends from a peripheral portion of a substantially disk-shaped panel portion outward to a reinforcing annular groove recessed inside the can and an outer wall of the annular groove. In the can lid that is integrally formed so that the inclined chuck wall part and the flange curl part whose outer peripheral part is curled are continuous, it is easy to make cornering deformation that becomes the starting point of buckling near the peripheral part of the panel part. The present invention is characterized in that a buckling inducing section is formed and a score line is formed near the buckling inducing section, the score line being broken by cornering deformation during buckling.
[0008]
According to the above configuration, when buckling occurs due to an abnormal increase in the internal pressure of the can, the buckling inducing section positively deforms the can lid in the buckling inducing section. When the score line formed in the vicinity is broken, the internal pressure of the can is immediately reduced, so that the occurrence of blow-off due to the breakage of the tightened portion is reliably prevented. Moreover, since the score line is provided only to the minimum necessary in the vicinity of the buckling induction part, the strength of the can lid does not decrease so much, and the score line can be easily formed in a state where buckling does not originally occur. It will not be broken.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a can lid of the present invention will be described in detail with reference to the drawings. In addition, about one embodiment of the can lid of this invention, FIG. 1: shows (A) the plane shape of the whole can lid, and (B) the longitudinal cross-sectional shape of the can lid along the BB line of A figure, FIG. 2 shows (A) a planar shape and (B) a longitudinal cross-sectional shape in the vicinity of the buckling inducing portion where the score line is formed, and FIG. 3 shows a planar shape similar to the score line shown in FIG. It shows each example (A) and (B) of different score lines. FIG. 4 shows (A) a planar shape and (B) a vertical cross-sectional shape in the vicinity of the buckling inducing portion on which a score line is formed, according to another embodiment of the present invention. FIGS. 5A and 5B show a state in which the can lid is cornered and deformed when buckling occurs.
[0010]
The can lid according to the present embodiment is used for a positive internal pressure can (positive pressure can) containing carbonated beverages or beer, etc., and is formed by press molding using a conventionally known molding die. As shown in FIG. 1 (A), each part of a panel part 2, an annular groove 3, a chuck wall part 4, and a flange curl part 5 is integrally formed from a metal plate material. As shown in FIG. 1 (B), with the inner side of an unused can lid facing down, the outer peripheral portion of the substantially disk-shaped panel portion 2 is outwardly directed downward ( An annular groove 3 for reinforcement is formed so as to be recessed (inside of the can), and the chuck wall portion 4 rises inclining outwardly so as to continue substantially flush with the outer wall of the annular groove 3, and the upper end of the chuck wall portion 4 Is continuous with the trumpet-shaped curved surface of the inner peripheral portion of the flange curl portion 5, Parts are curled downward.
[0011]
The can lid 1 is an unused product after being press-formed. Although not shown, the can lid is formed after an organic polymer sealing agent is applied to the back surface of the flange curl portion 5. It is placed on the flange portion of the main body (can body) and is double-wrapped around the flange portion of the can main body by the flange curl portion 5, so that the can main body can be used as an end plate portion (top lid or bottom lid) of the can. And is integrally fastened and fixed.
[0012]
The metal plate material for the can lid used as a material of the can lid 1 is a metal plate that has been rolled and then subjected to appropriate surface treatment or plating as necessary as a main material, and at least a surface on the inner side of the can. (Surface in contact with the contents) is formed with a resin film. As the metal plate, for example, an aluminum plate made of pure aluminum or an aluminum alloy (3004 material, 5052 material, 5082 material, 5182 material, etc.) A steel sheet material such as a chromic acid-treated steel sheet, a nickel-plated steel sheet, and a tin-plated steel sheet can be used. As the resin film, paints such as epoxy-phenol resin, epoxy-acrylic resin, vinyl chloride resin, polyethylene, polypropylene, polyester, polyamide, ionomer, etc., from the viewpoint of food hygiene, corrosion resistance, processability, and flavor. Resin films composed of one or two or more of thermoplastic resins such as those described above can be used.
[0013]
Incidentally, in the can lid 1 in which the panel portion 2, the annular groove 3, the chuck wall portion 4, and the flange curl portion 5 are integrally formed as described above, in the present embodiment, as shown in FIG. A buckling inducing portion that is easy to be horned and serves as a starting point of buckling at four positions around the periphery of the portion 2 at substantially equal intervals in the circumferential direction (90 ° intervals with respect to the center of the can lid). 6 is formed, and when the internal pressure of the can becomes abnormally high in the can in which the can lid 1 is tightly fastened, buckling occurs preferentially in the buckling inducing portion 6 so that buckling occurs. Is caused to occur.
[0014]
In the present embodiment, each of the buckling inducing portions 6 of the can lid 1 is formed by coining (coining), and as shown in FIGS. 2A and 2B, the plate thickness is reduced. It is formed as a coining part projecting upward (outside of the can). A score line 7 is formed on at least one of the buckling induction portions 6 so that the score line 7 is broken by the buckling deformation of the buckling induction portion 6. It is formed so as to cross an imaginary line L passing through the center of the lid 1 and the buckling inducing section 6.
[0015]
The planar shape of the score line 7 is, as shown in FIG. 2A, a straight line extending in a direction orthogonal to a virtual line L passing through the center of the can lid 1 and the buckling inducing section 6. However, the present invention is not limited to such a case. For example, as shown in FIG. 3 (A), it may be formed in an arc shape, or as shown in FIG. 3 (B), in a broken line shape. By pointing both ends of the score line 7 toward the center side of the can lid 1 in such a manner, for example, in a case where the score lines 7 are formed for all the buckling inducing portions 6 When all of the score lines 7 are broken, the broken ends of the score lines 7 are connected in the circumferential direction at the peripheral portion of the can lid 1 so that the can lid 1 is greatly opened. Can be prevented.
[0016]
Regarding the state of occurrence of buckling (state of cornering deformation) in the can lid 1 in which the buckling inducer 6 is formed at four locations, first, the internal pressure of the can becomes abnormally high and the first buckling occurs. Thus, as shown in FIG. 5A, the cornering deformation portion 10 is formed at one place. If the internal pressure of the can continues to be abnormally high thereafter, a second buckling occurs sequentially over the entire circumference of the can lid, and finally, as shown in FIG. The cornering deformation portion 10 is formed in all cases.
[0017]
When such a can lid 1 is buckled, each of the buckling inducing portions 6 serves as a starting point for causing a cornering deformation. In the present embodiment, with respect to the easiness of cornering deformation (deformation resistance) in the portion 6, in the present embodiment, by providing a difference in strength between the buckling induction portions 6, the angle of each buckling induction portion 6 during buckling is provided. Priority is given to out-deformation. Specifically, of the four buckling inducing portions 6 formed at four locations, the strength at two locations symmetric with respect to the center of the can lid is weaker than the strength at the other two symmetric locations (deformability). Is made large, that is, easily deformed), and this portion is preferentially used as a buckling starting point.
[0018]
Regarding a specific method for providing a strength difference in the ease of deformation (deformation resistance) in each buckling inducing section 6 by the coining section, the height (depth) of the protrusion of the coining section is changed, or coining is performed. This is possible by changing the plate thickness of the portion. The higher the height of the protrusion (the deeper), the easier it is to deform, and the thinner the plate, the easier it is to deform.
[0019]
As described above, the strength difference is provided between the buckling inducing portions 6 with respect to the ease of the cornering deformation, whereas the score line 7 formed near the buckling inducing portion 6 is different from the buckling inducing portion 6 in FIG. 6 are formed only on those whose easiness of squaring deformation is relatively small (hard to deform). In other words, of the buckling inducing portions 6 formed as coining portions, each of the two buckling inducing portions 6 in which the coining portion is relatively hardly deformed (either one of them may be used). 2 (A) and 2 (B), a score line 7 is formed so as to cross an imaginary line L passing through the center of the can lid 1 and the buckling inducing section 6. Specifically, FIG. The score line 7 is formed so as to cross the coining part (projecting thin part) which is the buckling inducing part 6 (may be within the coining part).
[0020]
The position of the score line 7 formed in the vicinity of the buckling inducing section 6 (in this embodiment, so as to cross the coining section) is determined according to the rolling direction of the metal plate of the can lid 1 (0 ° with respect to the rolling direction). Direction), on a virtual line passing through the center of the can lid in the rolling direction (a state crossing the virtual line), or on a virtual line passing through the center of the can lid in a direction perpendicular to the rolling direction (a state crossing the virtual line). ) May be arranged at random regardless of the rolling direction. However, in the present embodiment, as shown in FIG. The buckling inducing portions 6 are arranged so that a virtual line L passing through the rolling direction X is at an angle of 45 ° with respect to the rolling direction X. A score line 7 is formed on the buckling trigger section 6 above) To have.
[0021]
According to the can lid 1 of the present embodiment in which the buckling inducing section 6 and the score line 7 are formed as described above, a specific portion (the buckling inducing section 6) can be reliably used as the buckling starting point. In addition, by forming the minimum required number of score lines 7 only for such a specific portion (the buckling inducing section 6), a large number of score lines are formed to greatly reduce the strength of the can lid. Without causing the buckling, the score line 7 can be surely broken when buckling occurs, and as a result, blow-off can be reliably prevented from occurring due to a decrease in the internal pressure of the can due to the breakage of the score line 7. it can.
[0022]
In this embodiment, since the score line 7 is formed in the peripheral portion of the panel portion 2 of the can lid 1 (within the coining portion formed in the peripheral portion of the panel portion 2), the winding of the can lid is performed. Compared to the case where score lines are formed in the part to be tightened, when the can is accidentally dropped, the score lines do not directly contact the ground, and the breakage of the score lines due to a drop impact is prevented. In addition, when the score line is broken due to the occurrence of buckling, the breakage of the score line does not destroy the wound portion and does not cause blow-off.
[0023]
In the present embodiment, the score line 7 is formed so as to cross the imaginary line L extending in the radial direction of the can lid 1 so as to pass through the center of the can lid 1 and the buckling inducing section 6. As the buckling occurs, the buckling-inducing portion 6 is deformed to be square, so that the periphery of the panel portion 2 protrudes outwardly in the radial direction of the can lid (mountain). When the score line 7 is deformed into a bent shape, the score line 7 crosses the ridge-shaped portion, so that the score line 7 is reliably broken. On the other hand, when the score line is extended in the radial direction of the can lid, there is a possibility that the score line is simply bent in a ridge shape at the score line portion, and the score line is not broken.
[0024]
Further, in the present embodiment, the buckling inducing portions 6 are formed at a plurality of locations (four locations) to provide a difference in strength in the ease of deformation at each of the buckling inducing portions 6, and among the buckling inducing portions 6. Since the score line 7 is provided for the buckling inducing portion 6 having a small deformability (hard to deform), when the buckling occurs due to an abnormal increase in the internal pressure of the can, the deformable portion is easily deformed first. After the first buckling occurs and the internal pressure of the can is temporarily reduced by buckling deformation occurring in the buckling inducing unit 6, the internal pressure of the can gradually increases, and the buckling inducing unit 6 is difficult to deform. When the buckling deformation occurs and the second buckling occurs, the score line 7 can be broken, and as a result, the breaking of the score line 7 is suppressed until the internal pressure of the can rises to a level that causes blow-off. In , It is possible to prevent the breakage of the score line 7 in a state the can internal pressure is not so high.
[0025]
In addition, about the number of the buckling induction | guidance | derivation parts 6 provided in the whole can lid, one may be sufficient, but it is difficult to control the starting point of buckling reliably with one, while if there are too many, the can About 2 to 4 pieces are preferable because the pressure resistance of the lid is greatly reduced. Specifically, in the present embodiment, the buckling inducing portions 6 are formed at four positions, and the strength of two symmetrical portions with respect to the center of the can lid is higher than the strengths of the other two symmetrical portions. This portion is weakened (the deformability is increased, that is, easily deformed), and this portion is preferentially used as a buckling start point. Then, one score is provided for each of the two buckling inducing portions 6 having low deformability (which is difficult to deform), and a total of two scores (or one score is acceptable for any one of them). A line 7 is provided.
[0026]
Regarding the position of the score line 7, even on an imaginary line passing through the center of the can lid in the rolling direction (a state crossing the imaginary line), on the imaginary line passing through the center of the can lid in a direction orthogonal to the rolling direction (the imaginary line). May be arbitrarily arranged regardless of the rolling direction. However, in the present embodiment, the can lid 1 is formed at an angle of 45 ° with the rolling direction X of the metal plate of the can lid 1. Is formed on a virtual line L passing through the center of the score line (a state crossing the virtual line L), so that even if the remaining thickness of the score line 7 is relatively thick (the notch is shallow), the score line 7 is formed at the time of buckling. 7 is to be broken.
[0027]
That is, in a rolled metal sheet, it is a well-known matter that the strength in the direction at an angle of 45 ° with respect to the rolling direction is weaker than the strength in other directions. By forming the score line in the weak part, even if the remaining thickness of the score line is relatively thick, the score line can be broken at the time of buckling, and as a result, the remaining thickness of the score line can be reduced. Breakage of the score line and deterioration of the inner surface quality of the can lid due to the drop impact at the time of this can be prevented. In addition, in the direction of 45 ° with respect to the relatively weak rolling direction, buckling deformation at the time of buckling is likely to occur, so that the buckling inducing section 6 can more reliably control the position of the buckling starting point. it can.
[0028]
Further, in the present embodiment, the buckling inducing section 6 is positioned on an imaginary line L passing through the center of the can lid at an angle of 45 ° with the rolling direction X of the metal plate of the can lid 1, so that the buckling can be prevented. Since the cornering deformation is likely to occur, the buckling trigger 6 can be more reliably controlled by the buckling trigger 6 and the buckling trigger 6 can be loosely formed (specifically, for example, by a coining unit). Therefore, even if the height of the protrusion is reduced or the thickness of the plate is increased), it can be easily deformed by cornering, and as a result, the reduction of the pressure resistance of the can lid due to coining processing or the like can be suppressed. Can be. On the other hand, in the direction other than the 45 ° direction with respect to the rolling direction, it is necessary to relatively form the buckling-inducing portion in order to easily cause cornering deformation as a starting point of the buckling, and to do so. As a result, the pressure resistance of the can lid is reduced.
[0029]
As mentioned above, although one Embodiment of the can lid of this invention was described, this invention is not limited only to the above-mentioned embodiment, For example, about the number of buckling induction parts, the above-mentioned embodiment The number of positions is not limited to four, but may be one or more. The structure of the buckling inducing portion is not limited to the coining portion as described in the above-described embodiment. 4) may be a coining portion that is depressed in ()) or a coining portion in which the plate thickness is only partially reduced. Further, the coining portion is not limited to the coining portion, as shown in FIGS. 4 (A) and 4 (B). The buckling inducing portion 6 may be formed as a groove-shaped concave portion in which a corner of an inner upper edge (in other words, an outer peripheral edge of the panel portion 2) of the reinforcing annular groove 3 is partially cut out. , Or any other appropriate structure In addition, the positional relationship of the score line with respect to the buckling inducing section is not limited to the position on the buckling inducing section (for example, a position crossing the coining section). Needless to say, the design can be appropriately changed, for example, as long as the can lid is formed in a range where the can lid is deformed.
[0030]
【The invention's effect】
According to the can lid of the present invention as described above, forming a large number of score lines does not significantly reduce the pressure resistance of the can lid, and furthermore, the internal pressure of the can increases abnormally and buckling occurs. If this occurs, the score line provided at the minimum necessary near the buckling induction part is reliably broken, so that after the buckling occurs, blow-off occurs due to the breakage of the tightened part. Can be reliably prevented.
[Brief description of the drawings]
FIG. 1 is a plan view showing an entire can lid according to an embodiment of the can lid of the present invention, and FIG. 1 (B) is a longitudinal sectional view taken along line BB of FIG.
2 (A) is a plan view and FIG. 2 (B) is a longitudinal sectional view of the can lid shown in FIG.
3 shows examples (A) and (B) of other score lines having a planar shape different from that of the score line shown in FIG. 2 in the vicinity of the buckling induction portion of the can lid shown in FIG. Plan view.
FIGS. 4A and 4B are a plan view and a vertical cross-sectional view partially showing the vicinity of a buckling inducing section on which a score line is formed, according to another embodiment of the can lid of the present invention.
FIG. 5 is a perspective explanatory view showing (A) a state at the time of the first buckling and (B) a state at the time of the final buckling, with respect to the state of the cornering deformation of the can lid when the buckling occurs.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 can lid 2 panel portion 3 annular groove 4 chuck wall portion 5 flange curl portion 6 buckling inducing portion 7 score line L virtual line X passing through center of can lid and buckling inducing portion Rolling direction of metal sheet

Claims (4)

Outward from the periphery of the substantially disk-shaped panel portion, an annular groove for reinforcement recessed inside the can, a chuck wall portion inclined to the outer wall of the annular groove, and a flange curl in which the outer peripheral portion is curled. In the can lid integrally molded so that the buckling portion is continuous, a buckling inducing portion, which is a starting point of the buckling, is easily formed in the vicinity of the peripheral portion of the panel portion. A can lid characterized in that a score line that is broken by horn deformation during buckling is formed near a trigger portion. The can lid according to claim 1, wherein the score line is formed so as to cross an imaginary line passing through the center of the can lid and the buckling inducing section. The can lid is integrally formed using a rolled metal plate as a main material, and a score line is formed near an imaginary line passing through the center of the can lid at an angle of 45 ° with the rolling direction of the metal plate. The can lid according to claim 1 or 2, wherein The buckling inducing portions are formed at two or more places, and there is a difference in strength between the buckling inducing portions at each of the buckling inducing portions. The can lid according to any one of claims 1 to 3, wherein a score line is formed for a buckling inducing portion having a relatively small number.

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