JP2003205940A - Can lid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a can lid capable of improving pressure resistance of the lid, securing seaming safety and sealing properties even in the case where a conventional seaming device is used, making a can lid blank narrow, and reducing a gauge accompanied by a decrease in the thickness of a sheet. <P>SOLUTION: The can lid has a center panel, a reinforced annular groove, a chuck wall, and a curled part. In this can lid, the reinforced annular groove has outer side walls rising from a lower end arcuate part in a perpendicular state or in a substantially perpendicular state. A chuck wall consists of a first chuck wall portion having a protruding curved part which is connected to an upper end of the outer side walls and is positioned on the inside of the radius R<SB>1</SB>of curvature and having a protruding curved part which is positioned on the outside of the radius R<SB>2</SB>of curvature, and a second chuck wall portion having a protruding curved part and a steep slope part which are positioned on the outside of the radius R<SB>2</SB>of curvature. By this method of forming the can lid, engaging capability between the chuck wall and a seaming chuck is enhanced while maintaining improvement in pressure resistance by making the center panel narrow. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can lid, and more particularly to a can lid in which can lid material is saved.

[0002]

2. Description of the Related Art From the viewpoint of material cost reduction, it has been an important technical issue for a can manufacturer to minimize the amount of material used for a lid material, and various methods have been proposed. In order to reduce the lid material, from the viewpoint of the lid structure, it is possible to make the lid material thinner and reduce the surface area of the lid material, but these measures are naturally resistant to positive pressure or negative pressure in the can. (Deformation resistance) and container tightness can be secured,
Moreover, it is necessary to satisfy the conditions such as workability for winding and good usability.

Conventionally, as a means for improving the pressure resistance and reducing the thickness of the lid material, a reinforced annular groove is generally formed between the chuck wall and the panel surface. Since the shape of the continuous chuck wall has an important influence on the pressure resistance of the can lid, various shapes of the reinforced annular groove and the chuck wall have been recently proposed in order to further increase the pressure resistance. For example, as a form of the reinforced annular groove, the conventional reinforced annular groove has spread in a substantially V shape.
A structure in which the opening angle of the outer wall is made smaller than that of the conventional one so as to approach the vertical wall (for example, JP-A-8-192840 and JP-A-2000-109068), and the inner wall and the outer wall are configured substantially vertically. What was done (for example, utility model registration No. 25442 gazette, special table 11-5057).
No. 91), or those in which the inner wall is inclined and the outer wall is made substantially vertical (US Pat. No. 4,217,843, US Pat. No. 4,093,102) have been proposed.

It is generally said that the vertical and higher the outer wall of the annular reinforcing groove is, the more the pressure resistance against the internal pressure is improved. However, there is an inconvenience that a winding tightening failure occurs. In order to avoid this, the vertical angle of the outer wall must increase the opening angle of the chuck wall accordingly, but then the bending angle becomes large at the position where the outer wall and the chuck wall are high. However, there is a problem that the necking is likely to occur and the buckling is likely to occur due to the snapping deformation due to the increase in the internal pressure. Therefore, in the above-mentioned prior art, the outer height of the reinforced annular groove is made lower than that of the center panel to lower the bending position, or the outer wall is slightly inclined and slightly raised to reduce the bending angle. Therefore, it is not possible to adopt a means of making the inner wall and the outer wall of the reinforced annular groove substantially vertical and raising the outer wall.

Further, as a means for reducing the surface area of the lid material while maintaining the pressure resistance to save the lid material, the chuck wall is inclined at an angle of 30 ° to 60 ° to reduce the diameter of the reinforced annular groove. The above is proposed (Japanese Patent Publication No. 11-505791). By increasing the angle of inclination of the chuck wall and decreasing the diameter of the reinforced annular groove to reduce the area of the central panel surface, the pressure resistance is improved, the plate thickness can be reduced, and the blank diameter can be reduced. Although it is effective for saving the lid material, it is difficult to obtain sufficient contact resistance between the chuck wall and the seaming chuck by the current double winding device, and the seaming chuck and the seaming roll at the time of winding are also available. Since the gap angle with is large,
The backup at the time of winding is not sufficient, the winding portion is easily loosened by spring back, and it is not satisfactory in terms of winding stability and sealing performance.

[0006]

As described above, as a means for increasing the pressure resistance of the conventional can lid, it is proposed that the reinforced annular groove be vertically raised and the center panel diameter be made smaller. However, on the other hand, these measures have the merits and demerits of deteriorating the engagement with the seaming chuck at the time of winding as described above, and still fully utilize the advantageous functions of the both means. No can lid was obtained.

Therefore, in the present invention, the advantageous functions of the both means can be fully utilized to improve the pressure resistance due to the shape effect of the lid, and there is little jumping deformation during buckling of the lid, and An object of the present invention is to provide a can lid capable of ensuring the winding stability and sealing property even with a conventional winding device and capable of reducing the gauge of the can lid blank and reducing the gauge due to the reduction of the plate thickness.

[0008]

The can lid of the present invention for solving the above-mentioned problems is a can lid having a center panel, a reinforced annular groove, a chuck wall, and a curl portion, wherein the reinforced annular groove is perpendicular to a lower arc portion. Alternatively, the chuck wall has an outer wall that rises substantially vertically, and the chuck wall is composed of an inwardly convex curved portion having a curvature radius R ₁ and an outwardly convex curved portion having a curvature radius R ₂ connected to an upper end of the outer wall. It is characterized in that it comprises a first chuck wall portion and a second chuck wall portion composed of a curved portion and a steep portion which are convex outside the radius of curvature R ₂ . Thus, the outer wall of the reinforced annular groove is configured to rise vertically or almost vertically from the lower end arc portion to improve the pressure resistance, and the upper end of the outer wall of the reinforced annular groove and the above By setting the chuck wall that connects the curl portions to include a combination of two or more curves, even if the above-mentioned vertical rising outer wall is provided or is particularly high, the outside of the radius of curvature R ₂ of the chuck wall is provided. It is possible to effectively prevent the occurrence of constriction at the convex curved portion. Further, the chuck wall is configured such that the side that is connected to the curl portion is a steeply sloped portion so that it is connected to the curl portion, thereby improving the engagement with the chuck wall during winding and A can lid having excellent stability and sealing property can be obtained.

The height h ₂ of the outer wall is higher than the height h _{1 of the} inner surface of the center panel and preferably satisfies the relationship of h ₂ > h _{1. In} particular, h ₁ + t ≦ h ₂ ≦ 3.25 mm (however, It is desirable that t satisfies the relationship of (the thickness of the center panel). If the height h ₂ of the outer wall is smaller than h ₁ + t, the pressure resistance due to the reinforced annular groove is not sufficiently improved, and if it is 3.25 mm or more, the chuck wall cannot be sufficiently secured. . Further, the lower end arc portion of the reinforced annular groove has a radius of curvature r ₂ of 0.65 m.
It is desirable that the arc portion is m ≦ r ₂ ≦ 2.00 mm. A smaller radius of curvature is advantageous for improving the pressure resistance, but if it is too small, molding processing becomes difficult, so the above range is desirable.

The radius of curvature R of the chuck wall
₁ is R ₁ ≧ 1.85 mm, radius of curvature R ₂ is R ₂ ≧ 0.6
It is desirable that the arc portion has a diameter of 5 mm. With such a configuration, it is possible to more effectively prevent the occurrence of a constriction at the curved portion of the chuck wall which is convex outside the radius of curvature R _2. . In that case, a curved portion convex inside the curvature radius R ₁ of the chuck wall and the curvature radius R ₁
During the curved portion of the _second convex outwardly, be provided with a gentle slope portion which is inclined 30 ° to 60 °, the radius of curvature R ₁ and R
It is desirable in that the curved portion composed of _two is smoothly connected. In that case, the height h ₃ of the steeply inclined portion of the chuck wall is preferably 2.5 to 3.5 mm from the top surface of the curl portion. Further, when the ratio k of the center panel diameter to the can lid outer diameter is in the range of 0.75 <k ≦ 0.85, the engagement with the chuck wall is improved while maintaining the pressure resistance improvement due to the center panel diameter reduction. It is desirable because it can be increased.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an enlarged view showing a cross section of a main part of a can lid according to an embodiment of the present invention. The can lid 1 of this embodiment includes a center panel 2, a reinforced annular groove 3, a chuck wall 4, and a curl portion 5. Reinforced annular groove 3
It is vertical or substantially vertical inner walls are connected via a curved portion 10 of the curvature radius r ₁ to the peripheral portion of the center panel 2 1
1, a lower end arc portion 12 having a radius r ₂ and a vertical or substantially vertical outer wall 13, and the upper end of the outer wall 13 is connected to the chuck wall 4. The outer wall 13 and the inner wall 11 of the reinforced annular groove are preferably parallel to each other with respect to the axis (that is, vertical walls), but the outer wall 13 is 0 ° to 2 ° outward with respect to the axis, and the inner wall 11 May be inclined 0 ° to 2 ° inward with respect to the axis. The height h ₂ of the outer wall 13 must be higher than the height h ₁ of the center panel inner surface, and must satisfy the relationship of h ₂ > h ₁ , more preferably h ₁ +.
The condition of t ≦ h ₂ ≦ 3.25 mm (where t is the thickness of the center panel) is satisfied. Specifically, h ₂ is 0.23 to 1.00 than the inner panel height h ₁ of the center panel.
It is formed so as to be higher by mm.

The chuck wall 4 is located between the outer wall 13 of the reinforced annular groove 3 and the curl portion 5, and comprises a first chuck wall portion 15 and a second chuck wall portion 16. Is a curved portion 17 that is connected to the upper end of the outer wall 13 and has an inwardly convex radius of curvature R _1.
And a curved portion 18 that is convex outside the radius of curvature R ₂ and a connecting portion 19 that connects both curved portions. The connecting portion 19 is
More preferably, the inwardly convex curved portion 17 and the outwardly convex curved portion 18 are directly connected to each other, or the inwardly convex curved portion 17 and the outwardly convex curved portion 18 are gradually changed in radius of curvature. It is desirable to connect with one or a plurality of changed curves to form a curve that smoothly changes continuously from the inner convex to the outer convex. The connecting portion 19 may be an inclined portion that is inclined with respect to the vertical plane, and the inclination angle θ ₁ of the inclined portion is 3
It is 0 ° to 60 °, preferably 40 ° to 50 °. 30 °
If it is below, the effect of reducing the center panel diameter cannot be obtained, and
It becomes difficult to tighten the wire at 0 ° or more, and it is also disadvantageous in improving the pressure resistance.

Also, the second chuck wall portion 16
Is composed of an outwardly convex curved portion 18 and a steeply sloping portion 20, and is preferably formed by smoothly changing the curved portion 18 to the steeply sloping portion 20. The inclination angle θ ₂ of the steeply sloping portion 20 is It is desirable to incline 3 ° to 15 ° to the outside, and if it is 3 ° or less, fitting of the seaming chuck becomes difficult, while if it is greater than 15 °, a backup effect for the winding roll during double winding. Is not obtained and the tightening becomes loose. The first chuck wall portion 15 and the second chuck wall portion 16 described above can eliminate the bending that causes the constriction, relieve the stress concentration in the curvature changing portion, and improve the buckling strength.

The curved portion 17 of the first chuck wall portion 15
The radius of curvature R ₁ is preferably in the range of 0.65 mm to 2.0 mm, and when the radius of curvature R ₁ is 0.65 mm or less, the joint portion becomes sharp and stress is easily concentrated, which is not desirable. In addition, the upper limit of the radius of curvature R ₁ is limited by the position of the upper end of the outer wall 13, and if it is too large, the length of the outer wall 13 that rises vertically or almost vertically becomes short, and the radius of curvature R 1 also increases.
_{Since it} is difficult to form the _second curved portion 18, 2.0 mm or less is desirable. Further, the curvature radius R ₂ of the curved portion 18 is determined from the inclination angle of the steeply inclined portion 20 of the second chuck wall portion 16 and the curvature radius R ₁ of the curved portion 17. The height h ₃ of the steep slope 20 is in the range of 2.5 to 3.5 mm as a vertical distance from the top surface of the curl portion, and the height H ₃ of the can lid is about 35 to 55% with respect to the height H thereof. It is desirable that the position be within the range of 40 to 50%, which improves the backup property in the vertical portion of the seaming chuck during the secondary winding.

The center panel diameter D ₁ of the present invention is such that the ratio k (= D ₁ / D ₂ ) to the can lid outer diameter (curl portion outer diameter) D ₂ is in the range of 0.75 <k ≦ 0.85. Choose to be.
When the ratio k between the center panel diameter and the can lid outer diameter is smaller than 0.75, the center panel outer diameter becomes too small with respect to the can lid outer diameter, and the outer wall 13 is fixed to the lower end arc portion 1 of the reinforcing annular groove 3.
It cannot be provided so as to rise from 0 almost vertically or vertically. In addition, there is a problem that the inclination angle of the chuck wall must be increased beyond the above limit or the can lid height must be increased. On the other hand, if k is larger than 0.85, the effect of reducing the diameter of the center panel cannot be obtained.

FIG. 2 shows a cross section of a main part of the can lid according to the embodiment of the present invention when the can lid is wound and when internal pressure is applied. The state of the chain line shows the shape when the can is tightened, and in practice, when internal pressure is applied (0 .7
(MPa) is shown. As is apparent from FIG. 2, the shape of the can lid of the present invention when the internal pressure is applied is such that the center panel 2 expands upward and the radius of curvature r ₁ of the bending portion 10 becomes large, and as a result, the outer wall 13 has a large radius. The annular reinforcing groove 3 moves upward and radially inward with the curved portion 17 that is convex inside the radius of curvature R ₁ connected to the upper end as a fulcrum.

At this time, the inner wall 1 forming the annular reinforcing groove 3
1. Of the lower end arc portion 12 and the outer wall 13 rising vertically or substantially vertically, the inner side wall 11 and the lower end arc portion 12
Moves upward while maintaining its shape. On the other hand, the outer wall 13 changes from a vertical or nearly vertical state to a steep slope, but since the state is a steep slope, the pressure resistance does not decrease, and this tendency tends to occur especially as the height of the outer wall 13 increases. Appears. Further, since the inwardly convex curved portion 17 serves as a fulcrum, it is possible to effectively prevent the occurrence of constriction at the outwardly convex curved portion 18 when an internal pressure is applied. Further, since the side of the chuck wall 4 that is connected to the curl portion is the steeply inclined portion 20, the pressure resistance is similarly improved, and a can lid having excellent sealing performance can be obtained.

The can lid of this embodiment formed as described above has a conventional seaming chuck 21 having a steeply inclined portion working surface 22 and a gently inclined portion working surface 23, as shown in FIG. It can be wound with a normal seamer, and when the seaming chuck 21 is fitted to the can lid 1, the chuck wall 4
Since the gap inclination angle α between the steeply inclined portion 20 of the No. 1 and the steeply inclined portion working surface 22 of the seaming chuck is small, the first contacting portion with the seaming chuck is centered on the curved portion 18 from the start of winding, and the first contact is made. The winding can be performed without slipping between the can lid and the seaming chuck even with a strong resistance at the start of contact of the winding roll. Further, since the gap inclination angle between the steeply inclined portion 20 of the chuck wall 4 and the steeply inclined portion working surface 22 of the seaming chuck is small, the chuck wall 4 of the winding tightening portion has the steepness of the seaming chuck at the end of the primary winding. The inclined portion working surface 22 is backed up, and the primary winding can be completed more completely in a predetermined shape.

From this state, the secondary winding is performed by the second winding roll, so that the secondary winding is performed with the winding portion backed up by the seaming chuck from the start of the winding. As a result, it is possible to perform tightening with a stronger pressure contact force, and the wound part is firmly formed. Therefore, the amount of spring back after completion of winding is small, and firm winding can be achieved without loosening the winding portion.

[0020]

EXAMPLE Next, as an example, a can lid of the form shown in FIG.
Further, as Comparative Example 1, a can lid in which the can lid shape described in Japanese Patent Publication No. 11-505791 is changed to have a can lid outer diameter substantially similar to that of Example 1, and a conventional can lid as Comparative Example 2, The dimensions are shown in Table 1, and the relationship between the internal pressure change and the amount of deformation of the central portion of the center panel was examined. The result is shown in the graph of FIG. In addition, FIG. 4 is an overlapping comparison for clarifying the difference in the shape of the can lid between Example and Comparative Examples 1 and 2, and the solid line indicates the can lid 1 of Example 1,
The one-dot chain line represents the can lid 30 of Comparative Example 1, and the dotted line represents the can lid 31 of Comparative Example 2.

[0021]

[Table 1]

The deformation amount of the central portion of the center panel with respect to the rise of the internal pressure in the can lids of the above-mentioned Examples and Comparative Examples 1 and 2 is
As shown in FIG. 5, the present embodiment is obviously smaller. Particularly, the internal pressure of the example and the comparative example 2 is 0.1 MPa.
Therefore, there is a clear difference in the amount of deformation, and the difference gradually increases as the internal pressure increases. For example, in Comparative Example 1, when the internal pressure is 0.3 MPa, it is increased by about 0.3 mm, and at 0.5 MPa, it is expanded to about 0.5 mm. Further, as compared with Comparative Example 1, the deformation amount of the center panel is almost the same until the internal pressure is 0.3 MPa, but the deformation amount is obviously larger in Comparative Example 2 from the internal pressure of 0.4 MPa. . From the above results, it can be seen that the can lid of the present invention has a small amount of deformation of the center panel with respect to an increase in internal pressure and is excellent in pressure resistance.

[0023]

As described above, according to the present invention, the outer wall of the reinforced annular groove is configured to rise vertically or substantially vertically from the lower end arc portion, and the outer wall of the reinforced annular groove. By forming the chuck wall that connects the upper end and the curl portion with a combination of two or more curved lines and a steep slope portion, the advantageous function of both means is utilized to improve the pressure resistance due to the shape effect of the lid. It is possible to prevent the cap from slipping and deforming when buckling, and to secure the winding stability and sealing performance even with the conventional winding device, reducing the gauge of the can lid blank and reducing the gauge due to the reduction of the plate thickness. A possible can lid can be obtained. In particular, by using a means for making the outer side wall of the annular reinforcing groove vertical and higher than the center panel, the pressure resistance, winding stability, sealing performance,
It is possible to improve gauge down.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a can lid according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of the can lid according to the embodiment of the present invention when the can lid is wound and when an internal pressure is applied.

FIG. 3 is a cross-sectional view of an essential part showing a state before the first winding around the can body.

FIG. 4 is a cross-sectional view of a main part of a can lid of an example of the present invention and a can lid of Comparative Examples 1 and 2 which are overlapped for comparison.

FIG. 5 is a graph showing the relationship between the internal pressure of the can lid and the amount of deformation of the center part of the center panel in Examples and Comparative Examples.

[Explanation of symbols]

1 can lid 2 center panel 3 reinforced annular groove 4 chuck wall 5 curl portion 10 curved portion 11 inner side wall 12 lower end arc portion 13 outer side wall 15 first chuck wall portion 16 second chuck wall portion 17, 18 curved portion 19 connecting portion 20 Steep slope 21 seaming chuck 22 steep slope working surface 23 gentle slope working surface h ₁ center panel inner surface height h ₂ outer wall height of reinforced annular groove θ ₁ joint angle θ ₂ steep slope inclination curvature radius _D of the radius of curvature _{R 2} the curved portion 18 of the angle _{R 1} curved section 17 ₁ center panel diameter _{D 2} Kanfutagai径

Claims (8)

[Claims] 1. A can lid having a center panel, a reinforced annular groove, a chuck wall, and a curl portion, wherein the reinforced annular groove has an outer wall rising vertically or substantially vertically from a lower end arc portion, and the chuck wall is the first chuck wall portion consisting of a curved portion of the convex inner side of the curvature radius R ₁ on the outer side of the curved portion and the radius of curvature R ₂ of the convex connecting the upper end of the outer wall, and protruding to the outside of the curvature radius R ₂ A can lid characterized by comprising a second chuck wall portion comprising a curved portion and a steeply inclined portion. 2. The can lid according to claim 1, wherein the height h ₂ of the outer wall is higher than the height h _{1 of the} inner surface of the center panel, and the relationship of h ₂ > h ₁ is satisfied. 3. The height h of the outer wall_TwoAnd center panel
Inner height h₁Is h ₁+ T ≦ h_Two≤3.25 mm (however
And t satisfies the relationship of the thickness of the center panel)
The can lid according to claim 1 or 2. 4. The can lid according to any one of claims 1 to 3, wherein the lower end circular arc portion of the reinforced annular groove has a radius of curvature r ₂ of 0.65 mm ≦ r ₂ ≦ 2.00 mm. . 5. The radius of curvature R ₁ of the chuck wall is R ₁ ≧ 1.85 mm, and the radius of curvature R ₂ is R ₂ ≧ 0.65 m.
The can lid according to any one of claims 1 to 4, which is a circular arc portion of m. 6. A gentle inclining portion inclined by 30 ° to 60 ° between a curved portion convex inside the radius of curvature R ₁ of the chuck wall and a curved portion convex outside the radius of curvature R ₂ of the chuck wall. It has, The can lid in any one of Claims 1-5. 7. The can lid according to claim 1, wherein a ratio k between the center panel diameter and the can lid outer diameter is 0.75 <k ≦ 0.85. 8. The can lid according to claim 1, wherein the height h ₃ of the steeply inclined portion of the chuck wall is 2.5 to 3.5 mm from the top surface of the curl portion.