JPH10277676A - Production of easy opening can lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an easy opening can lid whose can opening force is stabilized and reduced and whose can opening property is improved. SOLUTION: By using a pair of dies composed of a punch with the curvature of radius of a knife edge being made less than 0.5 mm, a die and a blank holding plate, and by executing halfway stopping shearing on the condition of one side clearance between the punch and the die being more than 0 mm against a can lid 1, on each of the front face and the back face of the can lid 1, crack like opening notches 2a, 2b are formed within the range of the remaining wall thickness being 0.08 to 0.15 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of an easy-open can lid used for beverage cans and food cans, which is opened by breaking an opening formed in a can lid panel of a can body. It is about the method.

[0002]

2. Description of the Related Art As a can lid for cans containing various beverages such as beer, juice, coffee, etc., an easy-open can lid is widely used in which an opening formed in a panel of the can lid is broken by a finger and opened. I have. The easy-open can lid is roughly classified into a partial-open type can lid mainly used for beverage cans and a full-open type can lid mainly used for food cans.

[0003] Partial open type can lids are broadly classified into pull-top tab type can lids and stay-on tab type can lids. FIG. 6 is a schematic plan view showing an example of a pull-top tab type can lid. The opening of the pull-top tab-type can lid shown in FIG. 6 is performed as follows. That is, a rivet mechanism 8 is provided at the center of the central panel 7 of the can lid 1 made of a metal plate such as steel or aluminum.
By pulling up the tab 9 fixed by the above, the operative end of the tab 9 pushes down the break opening 10 in which the opening groove 11 is cut in the central panel portion 7 by leverage. As a result, the opening groove 11 is broken, and by further pulling the tab 9, the broken opening piece becomes the can lid 1.
Completely separated from

FIG. 7 is a schematic plan view showing one example of a stay-ion tub type can lid. The opening of the stay-ion tub type can lid shown in FIG. 9 is performed as follows. That is, by pulling up the tab 9 fixed to the center of the central panel portion 7 of the can lid 1 by the rivet mechanism 8, the breaking opening 10 in which the opening groove 11 is engraved in the central panel portion 7 is formed. By this action, the working end of the tab 9 is pushed down. As a result, the opening groove 11 breaks, and furthermore, the breaking is advanced by pulling up the protruding end of the tab 9, and a part of the breaking opening piece generated at that time is connected to the can lid 1 in the can. Push in.

A full-open type can lid has an opening groove engraved along the outer peripheral edge of the can lid, and pulls up a tab fixed to a panel portion near the outer peripheral edge of the can lid, thereby pulling a top. As in the case of the type, the opening piece is separated from the can lid.

[0006] The formation of the opening groove in the above-mentioned easy-open can lid is conventionally performed as follows.
That is, as shown in FIG. 8, a processing tool 12 having a blade-like projection with a predetermined opening contour is used, and a depth of 1/2 or more of the thickness of the lid plate 13 from the surface side of the can lid. Pressing with a high load such that the opening groove is formed. Thus, a groove 14 having a V-shaped cross section is formed.

[0007]

[0006] Pulling up the tab for opening the above-mentioned conventional easy-open can lid requires considerable force, and it is not easy for children and women to open the can. In order to reduce the tab pulling force at the time of opening the can and to easily open the can with a fingertip, a V-shaped groove 1 formed in the lid plate is required.
The shape of the tip of 4 may be sharpened. However, since the V-shaped groove 14 is formed by press working, the shape of the tip is limited, and the radius of curvature of the tip is around 0.05 mm. Therefore, the lifting force of the tab cannot be reduced until the child or woman can easily open the can.

As a countermeasure against the above-mentioned problem in forming the opening groove by pressing a working tool having a cutting edge-shaped projection, for example, Japanese Patent Publication No. 55-10454,
Japanese Patent Publication No. 3-71500, Japanese Patent Publication No. 3-71501, etc. have been proposed, but none of the above proposals has sufficiently reduced the tab lifting force.

Further, Japanese Unexamined Patent Publication No. Hei 3-5890, Japanese Unexamined Patent Application Publication No. Sho 62-235053, Japanese Unexamined Patent Application Publication No. Hei 2-179329, and the like have disclosed tabs by combining a thickness reduction process and a process from the inner side of a can lid. Although a method of reducing the lifting force has been proposed, also in the above-described method, the shape of the tip of the V-shaped opening groove is limited from the viewpoint of wear and breakage of the processing tool, and a sufficient stress concentration at the time of opening. Cannot be realized.

Japanese Patent Application Laid-Open No. Hei 8-224626 proposes a method of forming an opening groove having a shape different from a V-shaped opening groove by combining compression, tension, and shearing. However, in this method, since the wrinkle holding plate is not used, the material around the processed portion is subjected to tensile deformation at the stage of pressing the punch, resulting in a decrease in the thickness of the plate, resulting in a decrease in rigidity, and deformation of the groove at the time of opening. There was a problem that the concentration could not be performed and the opening force could not be sufficiently reduced.

Accordingly, an object of the present invention is to solve the above-mentioned problems, to stably reduce the can opening force, and to make it easy for even children and women to open cans. An object of the present invention is to provide a method for manufacturing a lid.

[0012]

According to the first aspect of the present invention, there is provided an easy-open can lid for opening a can lid by breaking an opening formed in a can lid panel of a can body. A pair of dies comprising a punch and a die having a blade edge curvature (R) of 0.5 mm or less and a wrinkle holding plate, and a one-side clearance (C) between the punch and the die being 0 mm or more. By applying a centering shearing process, the remaining plate thickness (t _R ) is 0.0
It is characterized in that a crack-shaped notch for opening within a range of 8 to 0.15 mm is formed.

According to a second aspect of the present invention, a pair of dies each comprising a punch and a die having a curvature (R) of a blade edge of 0.5 mm or less and a wrinkle pressing plate are provided with respect to the opening of the can lid panel. By using and performing middle stop shearing under the condition that the one-side clearance (C) between the punch and the die is 0 mm or more, the remaining plate thickness on both surfaces of the opening is 0.12 to 0.12.
A notch having a thickness in the range of 0.18 mm is formed, and then the opening is press-formed with a flat mold to form a crack having a residual thickness (t _R ) in the range of 0.08 to 0.15 mm. Is characterized in that the notch for opening is formed.

[0014]

Next, a method of manufacturing an easy-open can lid according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing one embodiment of a method for manufacturing an easy-open can lid according to the first aspect of the present invention.

According to the first aspect of the present invention, as shown in FIG. 1, a punch 3 and a die 4 each having a blade edge having a curvature (R) of 0.5 mm or less, and Using a set of molds consisting of the plate 5, wrinkle holding is performed by the wrinkle holding plate 5, and the middle stop shearing process is performed under the condition that the clearance (C) between the punch 3 and the die 4 on one side is 0 mm or more. As shown in the cross-sectional view of the notch portion for opening in FIG. 3, each of the front surface 1 a and the back surface 1 b of the can lid 1 has a notch for opening different from the groove for opening of the conventional can lid, and has a remaining plate thickness (t _R ). Form crack-shaped opening notches 2a and 2b in the range of 0.08 to 0.15 mm.

If the one-side clearance (C) between the punch 3 and the die 4 is less than 0 mm, a crack-shaped notch for opening cannot be formed. On the other hand, if the curvature (R) of the cutting edge of the punch 3 and the die 4 exceeds 0.5 mm, it becomes impossible to form a predetermined cut stably. Therefore, the curvature (R) of the cutting edge of the punch 3 and the die 4 is
It is necessary to perform the centering shearing process under the condition that the clearance (C) between the punch 3 and the die 4 is 0 mm or more, with 0.5 mm or less.

In the middle stop shearing processing, it is necessary to apply wrinkle control by the wrinkle control plate 5. In other words, by applying a wrinkle press during the center stop shearing, material deformation in the peripheral part is suppressed, and strain is concentrated on a sufficiently narrow range of material near the shoulder of the punch and the die, so that a sharp crack-shaped opening is formed. Notches can be formed.

FIG. 5 shows the remaining plate thickness (t) of the opening groove._R) And open
It is the graph which showed the relationship with can power. The opening force is
Opening force in case of middle stopper shearing process of the present invention and conventional V-shape
To the ratio to can opening force in the case of groove processing (medium stop shear / V-shaped groove)
Therefore, it was expressed. As is clear from FIG.
Remaining thickness (t_RThe thinner the), the lower the opening force. But
In addition, the remaining thickness of the opening groove (t)_R) Is less than 0.08mm
If it becomes too thin, the can is broken due to external impact, etc.
May occur. On the other hand, the remaining thickness of the opening groove
(T_R) Is greater than 0.15 mm, the conventional V
A larger opening force is required than in the case of the groove. Therefore,
In the present invention, the remaining thickness of the opening groove (t) _R)
It was limited to the range of 0.08 to 0.15 mm.

According to the second aspect of the invention, after the can lid panel of the can body is subjected to the centering shearing process by the method shown in FIG. 1 described above, the flat molds 6 and 6 shown in FIG. Press molding is performed. As shown in FIG. 4, by such a middle stopper shearing process and a press molding process using a flat mold,
In each of the front surface 1a and the back surface 1b of the can lid 1, the remaining plate thickness (t
_R ) is in the range of 0.08 to 0.15 mm, and the crack-shaped opening notches 2a and 2b can be formed by flattening the front and back surfaces of the opening.

According to the second aspect of the present invention, the remaining plate thickness of the opening groove before the press molding by the flat mold is 0.12 to 0.12.
It needs to be within the range of 0.18 mm. If the remaining plate thickness of the opening groove before the press forming by the flat mold is not within the above range, the remaining plate thickness (t _R ) of the opening groove after the press forming by the flat mold is 0.08 to 0. .15 mm.

By subjecting the can lid 1 to the above-described processing, a crack-shaped notch as shown in FIGS. 3 and 4 is formed, as compared with the conventional method of press-forming with a press using a tool having a blade-shaped projection. The opening force can be reduced as compared with a V-shaped groove formed by a conventional method.

As described above, a crack-like notch having a stable can opening force and having a low opening force is formed on both sides of the can lid panel by middle-shearing or middle-shearing followed by press molding with a flat mold. In order to form, regardless of the thickness of the can lid,
It is an important requirement that the thickness of the remaining sheet after processing is within a certain range.

The material of the can lid is generally 0.
An aluminum plate having a thickness of 15 to 0.30 mm, a surface-treated steel plate having a metal plated surface, a steel plate having a resin film laminated on the surface of the metal plating, or the like is used.

[0024]

Next, the present invention will be further described with reference to examples and comparative examples. [Example 1] Hardness (HR30T) with a plate thickness of 0.22 mm
Is formed on the surface of a thin steel sheet having an amount of 2.8 g / m ² of an electrotin plating layer, and a metal chromium layer of an amount of 12 mg / m ² is formed on the electrotin plating layer by a chromate treatment; An electro-tin-plated steel sheet on which a chromate film composed of a chromium hydrated oxide layer in an amount of 10 mg / m ^{2 in} terms of metal chromium was formed was formed a groove for opening within the range of the present invention shown in Table 1. Specimen of a pull-top / tab-type easy-open can lid with a notch for opening formed under the conditions
Nos. 1 to 3 were prepared. For comparison, a sample of a pull-top / tab-type easy-open can lid having an opening notch formed under opening groove processing conditions outside the range of the present invention shown in Table 1 (hereinafter referred to as a comparison sample). Nos. 1 and 2) were prepared.

[0025]

[Table 1]

Example 2 A metal chromium layer in an amount of 120 mg / m ² was formed on the surface of a thin steel plate having a thickness of 0.22 mm and a hardness (HR30T) of 61 by chromate treatment, and a metal chromium layer The tin-free steel on which the chromate film composed of the chromium hydrated oxide layer in an amount of 15 mg / m ^{2 in} conversion was formed is shown in Table 2 under the groove processing conditions for opening within the range of the present invention shown in Table 2. Specimens Nos. 4 to 6 of the present invention of easy-open can lids of the Stion tub type in which opening notches having a shape were formed were prepared. For comparison,
Specimen No. 3 for comparison of an easy-open can lid of a Stion tub type having an opening notch of the shape shown in the table under the groove processing conditions outside the range of the present invention shown in Table 2 , 4 were prepared.

[0027]

[Table 2]

Example 3 A stony in which an opening notch was formed on the surface of an aluminum alloy plate (JIS A5052) having a thickness of 0.26 mm under the groove processing conditions shown in Table 3 within the scope of the present invention. -Specimens Nos. 7 to 9 of the present invention as tab-type easy-open can lids were prepared. For comparison, Table 3
Sample Nos. 5 and 6 were prepared for comparison with easy-open can lids of the Stion tub type in which notches for openings were formed under the groove processing conditions for openings outside the scope of the present invention.

Further, as shown in Table 3, for the tin-plated steel sheets used in the test specimens Nos. 1 to 3 of the present invention, a conventional die having an inverted trapezoidal cutting edge was used to form an opening groove. Comparative specimen No. 7 composed of a stion tub type easy-open can lid, specimen No. 4 of the present invention
To the tin-free steel used in No.6, add the comparative specimen N
o. Comparative specimen No. 8 consisting of a stion tub type easy-open can lid in which an opening groove was formed by the same method as in o. 7, and specimens Nos. 7 to 7 of the present invention.
No. 9 for the aluminum alloy plate used in No. 9
Comparative sample No. 9 comprising a Stion-tab type easy-open can lid having an opening groove formed in the same manner as in No. 7 was prepared.

[0030]

[Table 3]

The specimen of the present invention prepared as described above
With respect to the easy-open type can lids of Nos. 1 to 9 and comparative specimens Nos. 1 to 9, the load W when the opening groove was broken at the time of opening was measured. Then, the ratio (W / W9) to the opening load W9 of the comparative specimen No. 9 which is a general prior art was calculated as an index of the easy opening property, and is shown together with each of Tables 1 to 3. Was.

As is clear from Tables 1 to 3, Sample Nos. 1 to 9 of the present invention had an opening property evaluation (W / W9) of 0.5.
To 1.0, all of which were excellent in opening properties. On the other hand, Comparative Sample Nos. 1, 3, 5, 7, and 8 each had an evaluation of opening (W / W9) larger than 1 and were poor in opening. In Comparative Sample Nos. 2, 4, and 6, the opening properties (W / W9) were all 0.3 or less, and the opening load was too small. It was highly likely to occur and could not be put to practical use.

[0033]

As described above, according to the present invention,
By forming crack-shaped notches on both sides of the can lid, the opening force is reduced stably, and an easy-open can lid with excellent can-opening properties is obtained. Brought.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a processing method using a pair of dies including a punch, a die, and a wrinkle holding plate according to the method of the present invention.

FIG. 2 is an explanatory diagram showing press molding using a flat mold according to the method of the present invention.

FIG. 3 is a cross-sectional view of a notch portion for opening formed in a can lid panel of a can body, showing one embodiment of an easy-open can lid manufactured by the method of the present invention.

FIG. 4 is a cross-sectional view of an opening cut portion formed in a can lid panel of a can body, showing one embodiment of an easy-open can lid manufactured by the method according to the second aspect of the present invention.

FIG. 5 is a graph showing the relationship between the remaining thickness of the opening groove and the can opening force.

FIG. 6 is a schematic plan view showing an example of a pull-top / tab-type can lid.

FIG. 7 is a schematic plan view showing an example of a canion tub type can lid.

FIG. 8 is an explanatory view showing a conventional method for forming an opening groove in an easy-open can lid.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Can lid 2a, 2b Opening notch 3 Punch 4 Die 5 Wrinkle holding plate 6 Flat mold 7 Central panel 8 Riveting mechanism 9 Tab 10 Break opening 11 Groove for opening 12 Working tool 13 Cover plate 14 V-shaped groove

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuji Yamazaki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Yoshinori Yomura 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (72) Inventor Reiko Sugihara 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd.

Claims (2)

[Claims] 1. A curvature (R) of a cutting edge is 0.5 mm or less with respect to the opening of the can lid panel of the easy-open can lid which is opened by breaking the opening formed in the can lid panel of the can body. By using a pair of dies including a punch and a die and a wrinkle holding plate, and performing a middle-shearing process under a condition that one-side clearance (C) between the punch and the die is 0 mm or more, the opening portion is formed. Forming a crack-shaped opening notch having a residual plate thickness (t _R ) in the range of 0.08 to 0.15 mm on both surfaces of the easy-open can lid. 2. A curvature (R) of a blade edge is 0.5 mm or less with respect to the opening of the can lid panel of the easy-open can lid which is opened by breaking the opening formed in the can lid panel of the can body. By using a pair of dies including a punch and a die and a wrinkle holding plate, and performing a middle-shearing process under a condition that one-side clearance (C) between the punch and the die is 0 mm or more, the opening portion is formed. The remaining plate thickness is 0.12-
A notch having a thickness in the range of 0.18 mm is formed, and then the opening is press-formed with a flat mold to form a crack having a residual thickness (t _R ) in the range of 0.08 to 0.15 mm. A method for manufacturing an easy-open can lid, characterized by forming a notch for opening.