JPH09201634A - Manufacture of easily openable metallic can cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture of an easily openable can cover by situating the thinnest part at the top of an S-shaped bend. SOLUTION: In press-working the opening piece of an easily openable metallic can cover which is at least provided with a coating on one side corresponding to the inner surface of a can or with a resin film, the thinnest part of the cross section in the machining part is press-worked so that it may be displaced to either one of the non-machining sides in a 3%-40% of the length of the thin part with its center as the starting point; therefore, the shape of the shoulder part of the punch and die is formed using a part of a specified ellipse. In addition, the angle formed by the major axis of the ellipse is shifted for a prescribed angle in the punch and die; after press-working with the clearance between the two specified to the minor axis of the ellipse, press-back forming is performed, thereby forming a bent cross-sectional shape in the thinnest part for machining.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention cans a metal plate such as a steel plate or an aluminum plate, or a surface-treated metal plate obtained by subjecting a metal plate such as tin plating, a chromate film, a coating or the like and a resin laminate to a surface treatment. When used as a lid,
The present invention relates to a method for manufacturing an easily-openable can lid provided with an opening guide wire for facilitating can opening.

[0002]

2. Description of the Related Art An easily openable can lid used for beverage cans, general food cans, etc., which has a tab as shown in FIG. Conventionally, after punching a metal plate of a material into a basic lid shape, placing it on a flat lower die and pressing an upper die having a score processing blade of a pointed tip cross section formed in an opening line shape, as shown in FIG. The opening guide wire was formed by performing score processing to form a V-shaped groove in a cross section perpendicular to the opening guide wire. On the other hand, Japanese Patent Laid-Open No. 6-1
15548, JP-A-6-115546, and JP-A-6-122438.
It is said that by pressing a metal plate with the shoulder radius of the upper and lower dies as described above, the plate is thinned, and then further pressing back is performed to form a V-shaped waist fold portion to form an opening guide line. Manufacturing technology has been developed.

When score processing is performed on a laminated steel plate or the like having a resin coating on the plate surface so that the metal plate and the contents of the can do not come into contact with each other, the resin coating is damaged by the pointed score processing blade and the metal surface is exposed. In such a case, the latter pressing process and pushing-back process are mainly used because of the problem. However, the pressing work and the pushing back work do not have very good can openability, and further, there is a problem that the resin coating is broken in the resin-coated metal plate even by this processing method. Therefore, as disclosed in Japanese Patent Application No. 7-33248, the present applicants have a method of improving the can openability without destroying the surface resin film by performing a push-back process of bending after the press process into an S-shape. However, there was a demand for further improvement in can openability.

[0004]

By the above pressing and S-shaped pushing back, it is possible to reduce the thickness and form the bent portion without damaging the resin film on the surface of the metal plate. The present invention has been completed on the basis of the finding that the thinnest portion is brought to the apex of the S-shaped bent portion to further improve the can openability.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. (1) When pressing an opening piece of a metal can openable can lid,
The thinnest portion in the cross section of the processed portion is 3% to 40% of the length of the thinned portion starting from the center of the thinned portion in the cross section.
A metal easy-to-open with excellent openability, characterized by forming a bent shape at the thinnest processed part by pressing so that it is displaced to one of the non-processed parts and then performing push-back molding. Method for manufacturing can lid.

(2) When pressing an opening piece of a metal can openable can lid, the thinnest part in the cross section of the processed part has a length of the thinned part starting from the center of the thinned part in the cross section. In order to perform pressure processing so as to be displaced to the non-processed portion side of 3% to 40% of the thickness, the shape of the shoulder portion of the punch and the die is 0.1 to 5.0 mm in major radius and 0.05 in minor radius. ~ 4.0 mm
Of the ellipse of the punch and the die are shifted by 30 ° to 150 °, and the clearance between them is set to −3.0 to 0.5 times the minor radius of the ellipse. After that, by performing push-back molding, a bent cross-sectional shape is formed at the thinnest processed portion, and a method for manufacturing a metal easy-open can lid having excellent can open characteristics.

(3) At least one side corresponding to the inner surface of the can is coated, or the thickness is 10 to 100 μm and the breaking elongation is 100.
%, The thinnest part in the cross section of the processed part when pressing the opening piece of the metal easy-open can lid having a resin coating of
The thinnest part can be processed by pressing so as to displace from the center of the thinned part in the cross section to the non-processed part side of 3% to 40% of the length of the thinned part, and then performing push-back molding. A method for producing a resin-coated easily-openable can lid having excellent can-opening characteristics, which is characterized in that a bent shape is formed at the portion.

(4) At least one surface corresponding to the inner surface of the can is coated, or the thickness is 10 to 100 μm and the breaking elongation is 100.
% Of the resin plate, the thinnest part in the cross section of the processed part is pressed from the center of the thinned part in the cross section when pressing the opening piece of the easily opened can lid made of metal plate. 3% to 40% of the length of the punch, the shape of the shoulder portion of the punch and die is 0.2 to 5.0 mm with a long radius of 0 and a short radius of 0. 1 ~
It is formed by using a part of a 4.0 mm ellipse, and the angle formed by the major axis of the ellipse in the punch and the die is 30 ° to 15 °.
It is shifted by 0 °, and the clearance between them is -3.
A method for producing a resin-covered easy-can-open can lid having excellent can-opening characteristics, characterized by having a cross-sectional shape that is bent at the thinnest processing portion by performing push-back molding after pressing as 0 to 0 times. Is about.

Hereinafter, the present invention will be described in detail. In the present invention, a steel plate, an aluminum plate, or a metal plate obtained by coating or metal-plating tin or zinc on the surface of the metal plate, and laminating a resin film thereon is used. This resin film has a thickness of 10 to 100 μm and a breaking elongation of 100% or more. If the thickness is less than 10 μm, it may become too thin during processing and may be broken, and if it exceeds 100 μm, deformation and elongation of the metal plate may not be able to follow during processing and peeling may occur.
If the elongation at break is less than 100%, the metal plate may not be able to follow the deformation and elongation of the metal plate during processing and may break.
It is desirable to have an elongation of 0% or more.

Next, the processed shape will be described. A conventional processing method for thinning a metal plate is as shown in FIG. 10, in which upper and lower molds chamfered with an arc having a certain radius of curvature R _P , R _D are installed with a certain clearance, pressed, and pressed. The metal plate was pressed at the part. FIG. 11 is a residual thickness model view of the cross section of the metal plate after the pressing work, and the thinnest part with the smallest residual thickness is located at the center of the thinned processed part cross section (total length L). When the push-back process is performed thereafter, the thinnest portion is positioned in the middle between the upper and lower bent portions due to the push-back as shown in FIG. However, in this case,
The stress concentration due to bending and the brittleness of the material do not act on the thinnest portion where the material strength is weakest.

Therefore, by bending at the thinnest portion as shown in FIG. 1, stress concentration acts on the thinnest portion to reduce the can-opening force. In order to obtain the shape of FIG. 1, it has been found that the residual thickness, which has conventionally been distributed as shown in FIG. 11, is biased as shown in FIG. That is, it has been found that the shape as shown in FIG. 1 can be obtained by pressing the thinnest cross-section so that it is displaced from the center of the processed portion (total length L), and then performing push-back processing. Here, the ratio at which the thinnest part deviates from the center of the processed part: eccentricity ρ = {(L / 2) -s} /
3% -40% is suitable for L. This is because if ρ is less than 3%, the effect of shifting the thinnest portion is not obtained, and if it exceeds 40%, it becomes difficult to bend the thinnest portion, and the shape of FIG. 1 cannot be obtained.

At this time, the minimum residual thickness of the steel sheet after working is preferably 15 to 80 μm. This is because if it is less than 15 μm, the drop strength as an easily openable can lid cannot be secured and it cannot be practically used, and if it exceeds 80 μm, the can openability is poor. The minimum remaining thickness of aluminum plate is 40-200μ.
m is desirable, for the same reason as for steel plates, but it is desirable to use the above-mentioned value in consideration of the difference in material strength.

Next, the processing method will be described. FIG.
In the conventional pressing method using a die chamfered with a circular arc shown by 0, a left-right symmetrical residual thickness distribution as shown in FIG. 11 is obtained. Here, in order to obtain a distribution shape in which the residual thickness is uneven as shown in FIG. 2, as shown in FIG. 3, processing is performed which is characterized in that a part of an ellipse is used for the shoulder shape of the pressing die. Further, as shown in FIG. 3, the punch and the die are characterized in that the shoulder portion of the mold is formed in such a manner that the angle formed by the major axis of the ellipse is φ = 30 ° to 150 °. This is when the flat direction of the ellipse is the same (0 ° ≦ φ <30 °, 150 ° ≦ φ <180
This is because the residual thickness distribution becomes symmetrical and the biased distribution shown in FIG. 2 cannot be obtained. Normally, φ = 9 as shown in FIG.
Install and use at 0 °.

Here, in order to deviate the residual thickness distribution as shown in FIG. 2, the larger the ratio R _A / R _B of the major radius to the minor radius is, the better. However, when this value is large, the ellipse becomes sharp. Therefore, the resin film steel sheet is expected to hurt resin film apical a plate surface during processing, it is desirable _{1.5 <R a / R B <} 3. If the dimensions of the ellipse of the non-laminated steel sheet, the long radius: R _A = 0.1 to 5.0 mm, minor axis: R _B = 0.0
It is set to 5 to 4.0 mm. This has a radius of curvature of 0.0
If it is smaller than 5 mm, it becomes difficult to bend it as shown in FIG. 1 because the thinned length in the cross section is short, and therefore R _B ≧ 0.05 mm (FIG. 4). Further, if the radius of curvature of the mold is large, the thinned length in the cross section becomes long as shown in FIG. 5, so that the bending-back portion also becomes long and the opening can stroke becomes large.
_A ≤ 5.0 mm. Here, the can opening stroke is the amount of pushing until breakage, and the larger this value, the worse the can opening property.

For non-laminated aluminum plates,
Considering that the minimum residual thickness is larger than that of a steel plate, if the radius of curvature of the mold is smaller than 0.1 mm, it becomes difficult to bend the mold as shown in FIG. 1, so R _B ≧ 0.1 mm is desirable. The upper limit of the die radius is the same as that of the steel sheet because the residual thickness has no effect. Therefore, the size of the ellipse is the major radius: R
_A = 0.2 to 5.0 mm, minor axis: R _B = 0.1~4.
0mm is recommended. On the other hand, in the laminated material, the major radius: R _A = 0.2 to 5.0 mm, the minor radius: R _B = 0.1.
~ 4.0 mm. This is because when R _B ≦ 0.1, the coating on the surface of the metal plate is damaged, so the short radius of the ellipse is R _B ≧ 0.1.
For the same reason as the non-laminated material, the long radius is _RA
≦ 5.0 mm. These are the same for both steel plates and aluminum plates.

The punch and die thus formed are given a certain clearance: CL and pressed to carry out thinning processing with uneven residual thickness as shown in FIG. Here represented using multiples f of ellipse minor radius R _B clearance as CL = f × R _B. F = −3.
0 to 0.3 is desirable. Negative clearance here indicates that the punch and die are overlapping. f is -3.
If it is less than 0, the punch and the die are overlapped with each other, and the angle of the thinned portion is horizontal as shown in FIG. 6, so it may not be pushed back properly.
When f is larger than 0.3, the punch and the die are separated from each other, which makes it difficult to reduce the thickness as shown in FIG.

For non-laminated aluminum material, f is -3.0.
To 0.5. The upper limit of f is the same as that of the steel sheet, but in the case of aluminum, the minimum residual thickness is smaller than that of the steel sheet, and therefore f <0.5. For a laminated material, if the clearance is set to f> 0, the resin film on the surface of the metal plate may be damaged when thinning, so f
Is set to -3.0 to 0. This is the same for steel plates and aluminum plates. After thinning in this way, by further performing push-back processing from above and below, a push-back shape bent at the thinnest portion shown in FIG. 1 is formed, and an easily openable can lid having good openability is formed. .

[0018]

EXAMPLES Examples of the present invention will be described together with comparative examples.
The specifications of the metal plate used are shown in Tables 1 and 3. Eccentricity, minimum remaining thickness, can openability, film of easily opened can lid formed by changing the pressing condition for non-laminated material and thin laminated material, and then performing push-back processing The soundness evaluations are shown in Tables 2 and 4. The can openability is evaluated from the can open load and the amount of press until the can is opened. The film integrity is evaluated by passing an electric current through the resin film, and it is evaluated that the film does not break if the energization amount is 1 mA or less.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

According to the present invention, the can openability of the easily opened can lid is improved even in the manufacturing method by pressing and the short life of the score processing blade which has been a problem in the conventional score processing is improved. Is possible. Further, in the processing of a can lid that can be easily opened using a resin-coated metal plate, the can-opening property was improved by performing the processing without damaging the film on the surface. As a result,
The can openability of the can lid using the surface-coated steel sheet has been improved, and the can lid part that was made of aluminum can now be made steel. As a result, it is possible to produce at low cost a product that is suitable for recycling and that addresses environmental problems.

[Brief description of drawings]

[Fig. 1] Ideal processing cross-section,

FIG. 2 is a residual thickness model diagram for a desired sectional shape,

[Fig. 3] Pressing die and processing shape using an elliptical shape,

FIG. 4 is a diagram showing a case where an ellipse has a small radius of curvature;

FIG. 5 is a diagram showing a case where the radius of curvature of an ellipse is large,

FIG. 6 is a diagram showing a case where the upper and lower molds have a small clearance,

FIG. 7 is a diagram showing a case where the upper and lower molds have a large clearance,

FIG. 8 is a schematic view of an easily opened can lid,

FIG. 9 is a view showing a cross-sectional shape of an opening guide line by score processing,

FIG. 10 is a diagram showing a conventional pressing chamfered arc die and processing shape;

FIG. 11 is a model diagram of the residual thickness by conventional pressing.

FIG. 12 is a cross-sectional view in which a conventional pressed material is subjected to pushback processing.

Front Page Continuation (72) Inventor Masaaki Yano 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Co., Ltd. Technology Development Division (72) Inventor Teruaki Izaki 1-1 Hibatacho, Tobata-ku, Kitakyushu, Fukuoka Shin-Nihon Steel Works Co., Ltd. Yawata Works (72) Inventor Tetsuro Takeshita 1-1 Tobatacho, Tobata-ku, Kitakyushu City, Fukuoka Prefecture Nippon Steel Co., Ltd. Yawata Works (72) Inventor Koji Manabe Tobata-ku, Kitakyushu, Fukuoka Prefecture 1-1 Hibatacho Inside Nippon Steel Co., Ltd. Yawata Works

Claims (4)

[Claims] 1. When the opening piece of a metal can openable can lid is pressed, the thinnest portion in the cross section of the processed portion has the length of the thinned portion starting from the center of the thinned portion in the cross section. 3% of
~ 40% Metal with excellent can openability characterized by forming a bent shape at the thinnest processed portion by performing pressure processing so as to be displaced to any non-processed portion side and then performing push-back molding. A method for manufacturing an easily opened can lid. 2. When pressing an opening piece of a metal easily opened can lid, the thinnest portion in the cross section of the processed portion has a length of the thinned portion starting from the center of the thinned portion in the cross section. 3% of
-40% In order to perform pressure processing so as to be displaced to the non-processed portion side, the shape of the shoulder portion of the punch and die is 0.1 to 5.0 mm in major radius and 0.05 to 4.0 mm in minor radius. Of the ellipse of the punch and the die are shifted by 30 ° to 150 °, and the clearance between them is set to −3.0 to 0.5 times the minor radius of the ellipse. After that, by performing push-back molding, a bent cross-sectional shape is formed at the thinnest processed portion, and a method for manufacturing a metal easy-open can lid having excellent can open characteristics. 3. Coating on at least one surface corresponding to the inner surface of the can, or a thickness of 10 to 100 μm and a breaking elongation of 100%.
When pressing the opening piece of the metal easily openable can lid having the above resin coating, the thinnest part in the cross section of the processed part is the length of the thinned part starting from the center of the thinned part in the cross section. Opening property characterized by forming a bent shape at the thinnest processed portion by press-working so that it is displaced to the non-working part side of 3% to 40% of the A method for producing a resin-coated easily-opened can lid having excellent properties. 4. Coating on at least one surface corresponding to the inner surface of the can, or a thickness of 10 to 100 μm and a breaking elongation of 100%.
When pressing the opening piece of the metal plate easily opened can lid having the above resin coating, the thinnest part in the cross section of the processed part is
In order to perform pressing so as to displace from the center of the thinned portion in the cross section to the non-machined portion side of 3% to 40% of the length of the thinned portion, the shape of the shoulder portion of the punch and the die is changed. , Major radius 0.2 to 5.0 mm, minor radius 0.1 to 4.0
It is formed by using a part of an ellipse of mm, and the angle formed by the major axis of the ellipse in the punch and the die is shifted by 30 ° to 150 °, and the clearance between them is set to −3.0 to 0 of the ellipse minor radius.
A method for producing a resin-coated easily openable can lid having excellent can openability, characterized by having a cross-sectional shape that is bent at the thinnest processed portion by performing push-back molding after pressing as double.