JP2002178072A - Can-top - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce use of materials and to eliminate sealing defects or wrinkles in seaming can-tops by reducing the cutting diameter of a can-top material while the strength of the can-top is maintained, in a thin can-top formed with a reinforcing annular groove. SOLUTION: The chuck wall part 4 situated between the flange curl part 5 and the reinforcing annular groove 3 is composed of an upper wall part 4a extending from the inner edge curved wall part 5a of the flange curl part 5 and a lower wall part 4b continuing to the outer edge of the reinforcing annular groove 3. A bent part 4c dividing the upper and lower wall parts 4a, 4b is situated at the height lower than and close to the sealed part when the can-top 1 is seamed to a can body 10. The lower wall part 4b that is continuous to the upper wall part 4a through the bent part 4c is formed with an inclination gentler in the angel at least by 5 deg. or more compared with the upper wall part 4a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can lid fixed as an end plate portion of a can container to an open end of a can body by double winding, and more particularly to a positive internal pressure can (a positive pressure can) having a high internal pressure of the can. ) Relates to the structure of the can lid before winding.

[0002]

2. Description of the Related Art Positive internal pressure cans (positive pressure cans) having a high internal pressure, such as beverage cans containing sparkling beverages such as carbonated beverages and beer, or beverage cans in which liquid nitrogen is dropped when filling the content. In), since the shape of the can container can be maintained by the internal pressure of the can even if the plate thickness of the can container is reduced to a certain extent, the thickness of the can container should be reduced as much as possible from the viewpoint of economy and resource saving during can manufacturing. In the past, efforts have been made to reduce the amount of materials used, and similar reductions in the materials used have been made for the can lid, which is the end plate of the can container.

In this case, if the thickness of the can lid is reduced, the strength is reduced correspondingly. On the other hand, even if the thickness of the can lid is reduced, the strength of the can lid can be maintained. It is common practice to form a reinforced annular groove depressed downward (inside of a can) on the outer periphery of a can. Further, in a can lid having such a reinforced annular groove, a panel is formed by a high can internal pressure. In order to increase the depth of the reinforced annular groove, the side wall shape, the radius of the groove bottom, etc., it is necessary to increase the buckling pressure resistance so that the so-called buckling which deforms so that the part swells outward of the can is difficult to occur. Various proposals have been made in the past (for example, see JP-A-49-96887, Japanese Utility Model Application Laid-Open No.
JP-A-131931, JP-A-7-2248, JP-A-8-192840, JP-T-11-50579
No. 1).

[0004]

The can lid disclosed in Japanese Patent Application Laid-Open No. H11-505791 is a conventional can lid having a reinforced annular groove as described above.
Each can lid disclosed in other publications, or FIG.
Compared with the conventional can lid as shown in FIG. 6A, as shown in FIG. 6B, the flange curl portion 5 serving as a portion to be fastened to the can body and the reinforced annular groove 3 on the outer periphery of the panel portion 2 are formed. The inclination angle of the chuck wall portion 4 formed therebetween is formed to be much smaller (the inclination angle with respect to the vertical line is made larger).

[0005] By making the inclination angle of the chuck wall portion between the flange curl portion and the reinforced annular groove small as described above, even if a can lid having the same diameter is manufactured, it is difficult to manufacture a metal can lid. It is possible to reduce the diameter (cutting diagram) of the can lid material that is punched into a disk shape from the plate, and to reduce the material used by the amount that can reduce the area of the can lid material even if the thickness of the can lid is the same Can be achieved.

[0006] However, in such a can lid in which the inclination angle of the chuck wall portion is reduced, when the can lid is wound around the can body, the can lid is not moved by the chuck on the flange of the can body to which the lifter pressure is applied. On the other hand, in the can lid disclosed in Japanese Unexamined Patent Application Publication No. 11-505791, the chuck and the chuck wall portion of the can lid abut at a gentler inclination angle closer to the horizontal direction, and Since the tip of the chuck does not enter the groove of the reinforced annular groove, the can lid chuck fits (chuck fit).
Is weak in the horizontal direction, and the angle difference between the chuck wall of the can lid and the flange of the can body is small, so that the can lid placed on the flange of the can body is largely displaced in the horizontal direction. Because of this, the holding of the can lid on the flange of the can main body is unstable, and chuck slip tends to occur, so that there is a problem that poor tightening is likely to occur.

[0007] Further, at the time of such a can lid winding, in the first winding step in the double winding, at the beginning of the winding, it is almost vertical (usually inclined at about 4 ° to the perpendicular). The upper part of the chuck wall part is farther away from the chuck receiving surface as it goes upward, so that the chuck wall part of the can lid is bent according to the receiving surface of the chuck. And
Since winding is performed while the neck portion of the can body is largely reduced in diameter, there is also a problem that wrinkles are likely to be generated in the tightened portion of the chuck wall portion in the first winding process.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. More specifically, a thin can lid having a reinforced annular groove formed therein is maintained while maintaining the strength of the can lid. ,
The object is to reduce the material used by reducing the diameter (cutting diamond) of the can lid material, and to prevent poor winding and wrinkling when winding the can lid. It is.

[0009]

According to the present invention, in order to solve the above-mentioned problems, a substantially annular disc-shaped panel is formed with a downwardly reinforced annular groove formed on the outer periphery thereof, and an outer edge of the reinforced annular groove is formed. The chuck wall portion rises obliquely outward from the upper end of the chuck wall portion, and is located between the flange curl portion and the reinforced annular groove in the can lid before tightening in which the upper end of the chuck wall portion is connected to the curved inner wall portion of the flange curl portion. The chuck wall portion comprises an upper wall portion extending from the inner curved wall portion of the flange curl portion, and a lower wall portion connected to the outer edge of the reinforced annular groove, and the bent portion separating the upper wall portion and the lower wall portion is a can. The inclination angle of the lower wall portion, which is located at a height below and closer to the wind-fastened portion when the lid is winded around the can body and is continuous with the upper wall portion via the bent portion. But from the upper wall And it is characterized in that it is formed to be loose at least 5 ° or more.

[0010] According to the above structure, by making the inclination angle of the upper wall portion of the chuck wall portion steep (closer to the vertical), a chuck slip occurs when the can lid is tightened, or the chuck wall portion is tightened. Can be prevented from being bent or the neck portion of the can body can be greatly reduced in diameter, thereby preventing improper winding and wrinkling from occurring. On the other hand, the lower wall portion of the chuck wall portion can be prevented. By decreasing the inclination angle of the can lid (closer to the horizontal direction), the diameter (cutting diamond) of the can lid material can be reduced, and the material used can be reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a can lid according to the present invention will be described in detail with reference to the drawings. 1 shows a cross-sectional shape of a portion from a panel portion to a flange curl portion of a can lid before being wound, and FIG. 2 is a can lid before being wound. 3 shows a state before (A) and (B) a state after the can lid is fastened to the can body, and FIG. 4 shows a state after the can lid is formed. FIG. 5 shows an end state of the second molding step for molding the can lid. FIG. 6 shows respective examples (A) and (B) of a conventional can lid.

The can lid of this embodiment is used for a positive internal pressure can (positive pressure can) containing carbonated beverages, beer, etc., and is made of, for example, an aluminum alloy (5182-H3).
9) A metal plate for can-making having a thickness of 0.305 mm obtained by heat-sealing a film made of a mixed resin of polybutylene terephthalate and polyethylene terephthalate having a thickness of 20 μm on both surfaces of the metal plate is used as a material. It is cut into a blank and press-molded.

As shown in FIG. 1, the can lid of the present embodiment formed by press-forming the disc-shaped blank of a metal plate as a can lid material has a substantially disk-like A reinforced annular groove 3 is formed so as to be depressed (inside of the can), and a chuck wall portion 4 rises from the outer edge of the reinforced annular groove 3 so as to incline outward. The flange curl portion 5, which is continuous with the portion 5a and whose outer edge portion is curled inwardly downward as a curved wall portion 5b, is not shown, but after a sealing agent made of an organic polymer is applied to the back surface thereof. , FIG. 3 (B)
As shown in (2), it is double-tightened to the flange portion of the can body.

[0014] The metal plate for can making as a material for manufacturing the can lid is not limited to the above specific example,
Conventionally, those generally used in the field of cans can be appropriately used selectively. Examples of the base metal plate include aluminum plates and aluminum alloy plates such as 3004 material and 5182 material. In addition, the adhesion amount is 0.5 to 3.0 g.
/ M tin-plated steel sheet subjected to tin plating after chemical treatment ^2, the adhesion amount 0.3 to 2.0 g / m ² of nickel-plated steel plate plated with nickel after the chemical conversion treatment, each 0 as tin and nickel coating weight. 5 to 2.0 g / m ² , 0.01 to 0.
5 g / m ² of tin / nickel plated steel sheet which has been subjected to a chemical conversion treatment after plating in the order of tin and nickel, and the amount of deposited metal chrome is 50 to
200 mg / m ² , chromium oxide adhesion 5-30 mg / m
² There is a surface-treated steel sheet such as a chromium-chromate-treated steel sheet which is usually called TFS (tin-free steel) in terms of chrome.

As the protective coating of the resin coated on both sides of the metal plate, there are lamination of a thermoplastic resin film directly or through an adhesive primer, and coating of a resin paint. As the film, a polyester resin film is preferable. For example, a resin film having polyethylene terephthalate as a basic structure and a resin film made of a copolymer such as polyethylene isophthalate are used.

The thermoplastic resin film may be unstretched or biaxially stretched. However, the thickness of the resin film laminated on the inner metal surface of the can is limited in view of the corrosion resistance of the inner surface of the can. Although it depends on the content to be filled after the forming process of the can, it is difficult to secure sufficient corrosion resistance if the thickness is less than 8 μm, while if it exceeds 25 μm,
Although the corrosion resistance to the contents is sufficiently ensured, it is practically excessive quality and not economical.
μm (preferably 10 to 20 μm).

The coating resin applied as the protective coating may be any protective coating made of a thermosetting or thermoplastic resin, for example, a phenol-epoxy coating, an amino-
A modified epoxy paint such as an epoxy paint, a vinyl chloride-vinyl acetate copolymer, a vinyl or modified vinyl paint such as an epoxyphenol-modified vinyl paint, or a combination of two or more thereof is used.

Meanwhile, in the can lid 1 of the present embodiment as described above, the chuck wall portion 4 between the flange curl portion 5 and the reinforcing annular groove 3 extends from the inner edge curved wall portion 5a of the flange curl portion 5. The upper wall portion 4a and the lower wall portion 4b continuous with the outer edge of the reinforcing annular groove 3 are formed, and a bent portion 4c separating the upper wall portion 4a and the lower wall portion 4b is provided as shown in FIG. When the can lid is fastened, the lower wall portion 4b is located at a height lower than the wound portion and near the wound portion, and the lower wall portion 4b below the bent portion 4c is The inclination angle is formed to be at least 5 degrees or more than the portion 4a.

In the can lid 1 of the present embodiment, the panel portion 2 is provided on the outer peripheral portion of the panel portion 2 inside the reinforcing annular groove 3.
An annular bead 2a is formed to protrude upward (or downward) for reinforcing the rigidity of the inner wall 3a.
And the reinforcing annular groove 3 having a bottom wall 3b and an outer wall 3c are formed in a flat shape such that the bottom wall 3b has a flat portion in the width direction, and the flat bottom wall 3b is It is connected to the outer side wall 3c via a corner having a radius.

As for the detailed structure of each part of the can lid 1 of the present embodiment, as shown in FIG. 2, the outer wall 3c of the reinforcing annular groove 3 has a predetermined inclination angle θ1 with respect to a vertical line. As you can see, it slopes outward from bottom to top,
The inclination angle θ1 is set to be 2 ° or more and 10 ° or less. That is, if the inclination angle θ1 is less than 2 °, there is a possibility that the pressure resistance and the shuffling property (the amount of lateral displacement in which the stacked can lids do not block each other) when a plurality of can lids are stacked may be reduced. The inclination angle θ1 is 10
If the angle exceeds °, the buckling pressure resistance may be reduced.

Outer edge of reinforcing annular groove 3 (upper end of outer wall 3c)
The lower wall portion 4b of the chuck wall portion 4 that rises inclining outwardly through the curved portion 3d is configured so that the inclination angle θ2 with respect to the perpendicular is 30 ° or more and 45 ° or less. That is, if the inclination angle θ2 is less than 30 °,
When the position of the reinforcing annular groove 3 approaches the extension L of the upper wall portion 4a of the chuck wall portion 4 and the diameter of the panel portion 2 increases, the effect of reducing the cutting dia (the diameter of the can lid material) is not so large. On the other hand, when the inclination angle θ2 exceeds 45 °, the can lid material for forming the bent portion 4c of the chuck wall portion 4 at the time of preforming in the first molding step of can lid molding described later. Of the lower wall portion 4b is likely to be generated.

The inclination angle θ2 of the lower wall portion 4b of the chuck wall portion 4 is larger than the inclination angle θ1 of the outer wall 3c of the reinforcing annular groove 3 when θ2 is equal to or less than θ1. This is because the rigidity of the reinforced annular groove 3 may be reduced, and the buckling pressure resistance of the can lid may be reduced.

The upper wall portion 4a of the chuck wall portion 4 is inclined more steeply than the lower wall portion 4b with the bent portion 4c as a boundary, and the inclination angle .theta.3 with respect to the perpendicular thereof is determined by the inclination of the lower wall portion 4b. The angle is set to be smaller than the angle θ2 by 5 ° or more. That is, the upper wall portion 4
a is less than 5 °, the upper wall portion 4a and the lower wall portion 4b
6A is almost eliminated, and is substantially formed as one inclined wall, which is close to the shape of the conventional can lid as shown in FIGS. 6A and 6B. is there.

The inclination angle θ1 of the outer wall 3c of the reinforcing annular groove 3
And the inclination angle θ2 of the lower wall portion 4b of the chuck wall portion 4 and the inclination angle θ3 of the upper wall portion 4a are formed so as to satisfy θ1 <θ2 and θ2> θ3. It is necessary to make the lower wall portion 4b of the chuck wall portion 4 closer to the center of the can lid than the extension line L of the upper wall portion 4a, so that the cutting diagram ( The diameter of the can lid material) can be reduced. However, if the difference between θ2 and θ3 is too large, the position of the reinforcing annular groove 3 is too close to the center of the can lid, and the pressure resistance is reduced. Therefore, the difference between θ2 and θ3 is set to be smaller than 30 °. Is preferred.

As for the relationship between the bent portion 4c of the chuck wall portion 4 and the panel portion 2, the ratio (D4 / D3) of the diameter D4 of the panel portion 2 to the diameter D3 of the bent portion 4c is not less than 0.86 and not more than 0.90. Of the range. That is, when D4 / D3 is larger than 0.90, the diameter D3 of the bent portion 4c becomes closer to the diameter D4 of the panel portion 2 so that the inclination angle θ2 of the lower wall portion 4b is maintained in the above range. As a result, the groove width of the reinforced annular groove 3 is reduced.
When the can lid is tightened as shown in (B), the width of the tip (lower end) of the chuck 11 to be fitted into the groove of the reinforcing annular groove 3 must be narrowed accordingly. The tip of 11 is easily damaged,
The sharpened tip of the chuck 11 easily causes abrasion on the outer surface of the can lid.

On the other hand, when D4 / D3 is smaller than 0.86, the diameter D3 of the bent portion 4c is separated from the diameter D4 of the panel portion 2, so that the inclination angle θ2 of the lower wall portion 4b is increased or strengthened. It is necessary to increase the groove width of the annular groove 3. If the groove width of the reinforced annular groove 3 is increased, the pressure resistance of the can lid is insufficient, and the thickness of the can lid is reduced to compensate for the insufficient pressure resistance. When the inclination angle θ2 of the lower wall portion 4b is increased, the drawing ratio of the can lid material is increased at the time of forming the can lid, so that wrinkles are easily formed on the lower wall portion 4b.

As shown in FIG. 3 (B), when bending the can lid as shown in FIG.
In consideration of the fact that the neck portion of the can is reduced in diameter toward the receiving surface of the chuck 11, it is necessary to minimize the diameter of the neck portion of the can body 10 so that it can be tightened. Otherwise, wrinkling may occur. However, the upper wall portion 4a of the chuck wall portion 4 may be previously formed with the receiving surface of the chuck 11 so as not to reduce the diameter of the neck portion of the can body 10 during winding. When the inclination is set, when the can lid is placed on the flange portion of the can main body 10, there is no allowance, so that positioning becomes rather difficult. Therefore, regarding the relationship between the upper end diameter D2 of the chuck wall portion 4 and the diameter D3 of the bent portion 4c, the value of D2−D3 is 0.4 mm or more and 0.8 mm.
It is set to be in the following range.

The bent portion 4c of the chuck wall portion 4
The vertical distance H2 from the upper surface of the flange curl portion 5 to the bent portion 4c is larger than and close to the width (longitudinal width) W of the double tightened portion shown in FIG. That is, it is set so as to be located 0.1 mm to 0.5 mm below the lower end position of the double-winding portion when the can lid is wound, and is located above the bent portion 4 c of the chuck wall portion 4 (upper wall portion). 4a) by making the surface slightly wider than the width of the pressing surface of the tightening roll 12, FIG.
When the can lid is tightened as shown in (B), the upper wall portion 4a above the bent portion 4c abuts against the side surface (receiving surface) of the chuck 11, and the pressing of the tightening roll 12 is securely received to form a double. A winding portion is formed.

Specifically, the vertical distance H2 from the upper surface of the flange curl portion 5 to the bent portion 4c is 2.60 mm to 2.60 mm.
When the dimension H2 is set to be smaller than 2.60 mm, the width W (longitudinal width) of the double-wound portion has to be reduced, and the buckling pressure is accordingly reduced. If the strength is reduced and the internal pressure of the can is abnormally increased, there is a danger that, at worst, the buckling may break the tightening and cause the can to burst, while the dimension H2 is 4.
If it exceeds 25 mm, the lower wall portion 4b is shortened by that amount, and the reinforcing annular groove 3 is closer to the outer periphery of the can lid, so that the cutting diamond (diameter of the can lid material) is reduced and the material used is reduced. Decrease.

When the can lid is tightened as shown in FIG. 3B, the chuck 11 and the can lid abut on the upper wall portion 4a of the chuck wall portion 4 and the bottom wall 3b of the reinforced annular groove 3, respectively. The lower wall portion 4b of the chuck wall portion 4 is kept out of contact with the chuck 11, and the contact of the chuck 11 with the chuck wall portion 4 of the can lid is not brought into two-side contact with the upper wall portion 4a and the lower wall portion 4b. Like that.

The can lid 1 of the present embodiment having the above specific structure is manufactured by two steps of press molding. First, in the first molding step, as shown in FIG. In a state where the metal plate is sandwiched between the die core ring 21 as a fixed member and the knockout ring 22 as a movable member, the metal plate is sheared and punched into a disk-shaped blank by a punch cutter 23 as a movable member. The punch core 24 is moved downward toward the die core 25 as a fixing member and pressed, so that the flange curl portion having the inner edge curved wall portion formed before the outer edge is sufficiently curled, the upper wall portion of the chuck wall portion, and the lower portion. It is preformed into an intermediate product having a wall portion, a bent portion, and a panel portion formed with an annular bead portion.

Next, in the second molding step, the first
The intermediate product preformed in the molding step is placed on a first die core ring 26 which is a movable member as shown in FIG. From the state in which the inner wall curved part of the part and the lower wall part of the chuck wall part are sandwiched
The entirety thereof and the punch core 28 of the movable member are moved down to the die curl 29, the second die core ring 30, and the die core 31, which are the fixing members, and pressed to further press the outer peripheral curved wall portion of the flange curl portion and the annular reinforcing groove. And the forming of the can lid is completed.

As described above, the can lid 1 of the present embodiment manufactured through the first molding step and the second molding step has 20 metal plates on both surfaces of an aluminum alloy (5182-H39) metal plate.
Using a metal plate with a thickness of 0.305 mm obtained by heat-sealing a film of a mixed resin of polybutylene terephthalate and polyethylene terephthalate having a thickness of μm, and comparing with specific examples in which each part has the following numerical values Example (20
An 8-diameter current product, that is, a conventional 208-diameter aluminum alloy can lid) was examined.

[0034]

[Example] Blank diameter (cutting diamond) is 7
About the can lid molded from a 9.2 mm can lid material,
The diameter (curl outer diameter) D1 of the can lid before tightening is 68.3 m
m, the depth (counter sink depth) H1 from the upper end of the flange curl portion to the groove bottom of the reinforced annular groove is 6.6 mm, and the inner radius of curvature r of the corner connecting the bottom wall and the inner and outer walls of the annular groove.
1 and r2 are each 0.35 mm, the width of the flat portion of the bottom wall of the annular groove is 0.45 mm, the inner radius of curvature r3 of the inner curved wall portion of the flange curl portion is 1.78 mm, and the inner radius of curvature of the curved portion 3d. r4 is 0.5 mm, the height (panel height) H3 from the groove bottom of the reinforcing annular groove to the panel portion is 2.00 mm,
The diameter (inner diameter) D3 of the bent portion of the chuck wall portion is 5
9.5 mm, the inclination angle θ1 of the outer wall of the annular groove is 6 ° 5
0 ', inclination angle θ2 of the lower wall portion of the chuck wall portion
Is 36 ° 10 ′, and the inclination angle θ3 of the upper wall portion of the chuck wall portion is 19 ° 06 ′, and the width (longitudinal width) of the double-tightened portion between the can lid and the can body is manufactured. W is 2.
It was wound up to 67 mm.

[Comparative Example] For a can lid formed from a can lid material having a blank diameter (cutting diamond) of 81.9 mm, the diameter (curl outer diameter) D1 of the can lid before tightening.
Is 68.3 mm, and the depth (counter sink depth) H1 from the upper end of the flange curl portion to the groove bottom of the reinforcing annular groove is 6.
9mm, inside radius of curvature of groove bottom of annular groove is 0.50mm
(There is no flat bottom wall at the groove bottom of the annular groove), and the inner radius of curvature r3 of the inner curved wall portion of the flange curl portion is 1.78 m.
m, the height (panel height) H3 from the groove bottom of the reinforced annular groove to the panel portion (panel height) is 2.28 mm, and the inclination angle θ1 (θ3) between the outer wall of the annular groove and the chuck wall portion is 13 °.
(The chuck wall is not divided into the upper wall and the lower wall, but has the same slope as the outer wall of the annular groove.)
Was manufactured, and the can lid and the can body were tightly wound so that the width (longitudinal width) W of the double wound portion was 2.76 mm.

Each of the can lids of the embodiment and the comparative example in which the respective portions were formed as described above was placed on the end of the can body opening of the seamless can body having a diameter of 211 and double-tightened with a seamer. Beer with gas volume of 2.2
After filling in from the mouth and sealing with a cap, the actual can adjusted to have a can internal pressure of 265 kPa in a 35 ° C constant temperature chamber was set in a single drop tester with the can lid facing downward, and From the height of the floor to the iron floor (15c
m, 20 cm, 30 cm, and 40 cm, respectively, were dropped three times). As a result, the actual can in which the can lid of the example was double-sealed was also compared with the actual can of the comparative example, in which the conventional 208-diameter can lid (the current product having 208 diameter) was double-sealed. It was found that it had a drop strength of the order.

Further, the can lid of the embodiment was replaced with a 450 ml 211 can.
The double-sealed portion of the empty can which was placed on the end of the opening of the can body of the diameter seamless can body and double-sealed with a seamer was visually observed in detail, but no wrinkling was observed at all. Cut off the mouth of this empty can, clamp it as a test can in a pressure tester, pressurize it with air until buckling occurs, no air leakage due to improper tightening, measure the maximum value when buckling occurs As a result, 715.4 to 744.8 kPa (average 727.2 kPa)
Pa), which is sufficient for the conventional guaranteed withstand voltage of 617 kPa, which is a practical level.

According to the can lid of the present embodiment including the above-described examples, when the can lid is wound around the can main body, the diameter of the neck portion of the can main body can be reduced to a small value. The can lid can be double-sealed to the can body without causing wrinkles or poor tightening, and the drop strength and buckling pressure strength of the positive internal pressure can (positive pressure can) sealed with the can lid are sufficient. When manufacturing can lids, it is possible to reduce the diameter (cutting diamond) of a disk-shaped blank punched out as a can lid material even when manufacturing can lids of the same size, thereby reducing the amount of materials used. be able to.

In the can lid of this embodiment, the reinforcing annular groove formed on the outer periphery of the panel portion is formed in a flat shape such that the bottom wall has a flat portion in the width direction. When the lid is tightened, the tip of the chuck, which is relatively wide, is fitted into the groove of the reinforcing annular groove, so that the surface of the can lid (the bottom of the groove of the reinforcing annular groove) is damaged by the tip of the chuck. The tip of the chuck can be reliably pressed against the groove bottom of the reinforced annular groove, and the distortion in the radial direction due to the tightening of the can lid and the chuck slip of the can lid can be reliably prevented. result,
It is not necessary to make the width of the flange curl longer than necessary, and it is possible to perform double winding (mini seam) with a small winding width, and the size of the can lid itself against the opening of the same size can body Since the size can be reduced, the material used can be further reduced.

The embodiment of the can lid according to the present invention has been described above. However, the present invention is not limited to the above embodiment. For example, the can lid may protrude upward from the panel portion of the can lid. The formed reinforcing bead may be formed so as to protrude downward or may be omitted. Further, a weakened line or a pull tab may be provided on a panel portion of the can lid, and the bead may be implemented as an easy open end. Is possible,
Further, the molding of the can lid can be appropriately changed, for example, it is also possible to mold using a device for molding the can lid from a metal plate to an inverted state in one single reciprocating motion without preforming. Needless to say,

[0041]

According to the can lid of the present invention as described above, even if the plate thickness of the can lid is reduced, the drop strength and the buckling pressure resistance can be sufficiently ensured, and the wrinkles can be tightened. The can lid can be wound around the can body without causing poor or insufficient tightening, and the diameter (cutting diamond) of the can lid material can be reduced when manufacturing the can lid. Materials used can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal cross-sectional view showing a portion from a panel portion to a flange curl portion of a can lid before winding in one embodiment of the can lid of the present invention.

FIG. 2 is a longitudinal sectional view showing a detailed structure of a can lid shown in FIG. 1;

FIG. 3 is a longitudinal sectional view showing (A) a state of being placed on the can body before being fastened and (B) a state after being wound on the can body of the can lid shown in FIG. 1;

FIG. 4 is a longitudinal sectional view showing a first molding step for molding the can lid shown in FIG.

FIG. 5 is a longitudinal sectional view showing a second molding step for molding the can lid shown in FIG. 1.

FIG. 6 is a longitudinal sectional view showing a state in which each of the conventional can lids (A) and (B) is placed on a can main body before being wound.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Can lid 2 Panel part 3 Reinforced annular groove 3b Bottom wall (of reinforced annular groove) 4 Chuck wall part 4a Upper wall part (of chuck wall part) 4b Lower wall part (of chuck wall part) 4c (of chuck wall part) Bent part 5 Flange curl part 5a Inner edge curved wall part (of flange curl part) 10 Can body

Claims (2)

[Claims] A reinforced annular groove which is recessed downward is formed on an outer periphery of a substantially disk-shaped panel portion, and a chuck wall portion is inclined outward from an outer edge of the reinforced annular groove and rises, and an upper end of the chuck wall portion is raised. In the can lid before winding, which is continuous with the inner curved wall portion of the flange curl portion, an upper wall in which a chuck wall portion between the flange curl portion and the reinforcing annular groove is extended from the inner curved curved wall portion of the flange curl portion. Part and a lower wall part connected to the outer edge of the reinforcing annular groove,
The bent portion that separates the upper wall portion and the lower wall portion is located at a height that is lower than the wound portion when the can lid is wound around the can body and near the wound portion, and the bent portion. The can lid is formed so that an inclination angle of a lower wall portion connected to the upper wall portion through the upper wall portion is at least 5 ° or less than that of the upper wall portion. 2. The can lid according to claim 1, wherein the bottom wall of the reinforcing annular groove is formed in a flat shape having a flat portion in a width direction thereof.