JPH09234534A - Easy can-opening lid and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to unnecessitate the repair of the coating after a cut guide groove is formed. SOLUTION: A steel sheet having a resin film of 10-100μm in thickness and >=100% in breaking elongation in which TS is <=46kgf/mm<2> in the nominal stress, and the n-value is <=0.15 is pressed using upper and lower dies in which the shoulder radius of the dies for forming a cut guide groove of an opening piece shape in which the shoulder radius is 0.1-1.6mm, and the clearance is -1.6-0.3mm so that the thickness of the thinnest part is <=1/2 of the metal thickness before working. If the easy can-opening lid of steel sheet is put into practical use, a mono-metal can whose easy can-opening lid and body are made of steel is realized, and a product suitable for the recycle coped with the recent global environmental problem can be provided on the market.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lid for a metal container, and more particularly, to an easily openable lid that can be easily opened manually on a part or almost the entire surface of a can lid, and a method for producing the lid. It is used in a wide range of applications such as food cans.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 4A and 4B, a cutting guide groove 3 is formed between a lid body 1 and an opening piece 2,
An easily openable lid in which a part of the container lid can be easily opened manually is provided by placing the lid main body 1 on a flat lower mold and pressing a sharp blade having a required contour shape from the upper surface thereof, By cutting the blade edge into the lid body 1, a cutting guide groove having a V-shaped cross section shown in FIG. 5 was formed to obtain an opening shape. However, in this method, (1) the blade edge of the coating film previously applied for anticorrosion is broken because of an acute angle, and in the case of a steel lid, repair coating is required thereafter, resulting in high manufacturing cost. (2) When the steel sheet is machined, the tool life is short because of the sharp edge sharp machining.

As a means for solving these problems, the present inventors applied for Japanese Patent Application No. 7-33248. To this end, a steel plate having a resin film is processed by the present method, that is, "the shoulder radius of the cutting guide groove forming die forming the opening piece shape is 0.1 mm to 1.6 mm and the clearance is -1.
Using a mold having a diameter of 6 mm to 0.3 mm, the metal thickness of the thinnest part of the process is set to 1 of the metal thickness before the process with the shoulder radius of the upper and lower molds.
Processing method characterized by forming a cutting guide groove thinned to ½ or less.

However, since a steel sheet as described in Japanese Patent Application No. 7-33248 has a large n value or is hard, the tabs must be considerably raised and θ shown in FIG. 6 must be large (that is, If the cutting guide groove was not largely deformed), the initial breaking of the cutting guide groove did not occur. Therefore, it was found that even if the opening force was small, the opening piece could not be sufficiently pushed down by the tab after the initial breakage, and the angle φ of the opening piece shown in FIG. 7 was too small to be commercialized. To solve this,
Even if the small guide groove was deformed when the tab was slightly raised, it was necessary to improve it so that the initial fracture occurred.

[0005]

SUMMARY OF THE INVENTION In view of the current state of the art, the present invention provides an easily openable lid having good openability without destroying a thin resin film and a method for producing the lid. To aim.

[0006]

The gist of the present invention is as follows. (1) The resin film has a thickness of 10 μm to 100 μm and a breaking elongation of 100% or more, and the TS is 46 kgf / m at the nominal stress.
A steel plate having m ² or less and an n value of 0.15 or less has a shoulder radius of a cutting guide groove forming die forming an opening piece shape of 0.1 or less.
mm-1.6mm and clearance -1.6mm-
A cutting guide groove in which the metal thickness of the thinnest part is thinned to 1/2 or less of the metal thickness before processing, by pressing and forming a plate with the shoulder radius of the upper and lower molds using a 0.3 mm die. A method for producing an easily-openable lid, which comprises forming. (2) The resin film has a thickness of 10 μm to 100 μm and a breaking elongation of 100% or more, and the TS is 46 kgf / m at the nominal stress.
It is an easily openable lid that does not require repair coating using a steel sheet having an m ² or less and an n value of 0.15 or less.

Hereinafter, the present invention will be described in detail. The present invention
It is an invention achieved by a combination of materials and processing methods.
You. First, the material will be described. Steel plate used in the present invention
Is usually the plate thickness t₀: 0.150 to 0.300 mm range
Surrounded by The base material of the steel plate has a nominal stress of TS of 46 kg.
f / mm^Two A steel plate having an n value of 0.15 or less
Used. TS is 46 kgf / mm^Two Steel plate that is super broke
The breaking strength is too high, so the tab should not be lifted more than 35 °
Then, the initial breaking did not occur on the cutting guide surface. For this reason,
Even if the opening force is small, a tab is sufficient for the opening piece after the initial breaking.
It cannot be pushed down, and the angle of the opening piece shown in Fig. 7 is too small.
It turns out that it cannot be commercialized. Therefore, the upper limit of TS
46 kgf / mm ^Two And Also, since the n value is 0.15
Even for large steel plates, if you do not lift the tab by more than 35 °,
No initial breakage occurred on the cutting guide surface. This cause is n
If the value is large, the deformed part will be work hardened and the deformation will not proceed easily.
The deformation spreads over a wide range, making it difficult for fracture to occur.
Presumed to be Therefore, the upper limit of the n value is set to 0.15.
Was.

The resin of the resin film on the can lid has a thickness of 10 to 10.
A material having 100 μm and a breaking elongation of 100% or more is used. If the thickness is less than 10 μm, it may be too thin during processing and may be broken. If it exceeds 100 μm, elongation of the steel sheet cannot be followed during processing and the steel sheet is peeled off. Also, breaking elongation 100
If it is less than%, the elongation of the steel sheet cannot be followed and the steel sheet may be broken during processing.

Next, the processing method will be described. A steel sheet having this resin coating and having a TS of 46 kgf / mm ² or less and an n value of 0.15 or less is press-formed, and the metal thickness of the thinnest processed portion is 1/2 or less of the metal thickness before processing. Thin. FIG. 1 shows a sectional view of the cutting guide surface that has been pressed.
At this time, the reason why the shoulder radii of the upper and lower molds for forming the cutting guide groove forming the opening piece shape are set to 0.1 mm to 1.6 mm will be described. When the shoulder radius is smaller than 0.1 mm, the resin film is damaged at the shoulder radius and sufficient corrosion resistance cannot be obtained unless the paint is repaired. On the contrary, when the shoulder radius is larger than 1.6 mm, the cutting groove machined with the shoulder radius has an excessively gentle radius R, so that stress concentration is less likely to occur at the time of opening the can and the can openability of the can lid is improved. Since it deteriorates, it is set to 1.6 mm or less. Further, in the conventional method of forming the V-shaped cutting guide groove with the sharp blade, the resin film is cut by the sharp blade.

Next, the clearance between the punch and the die-
The reason why it is limited to 1.6 mm to 0.8 mm will be shown. -1.
If it is less than 6 mm, the compressive stress becomes too large, the resin film is damaged, and sufficient corrosion resistance cannot be obtained unless the paint is repaired. On the other hand, if it is larger than 0.3 mm, the clearance is too large and the steel plate breaks if the metal thickness of the thinnest part to be machined is 1/2 or less of the metal thickness before machining.

At the time of processing, the peripheral edge portion of the opening piece is pressed between the upper and lower molds so as to reach a desired thickness, thereby forming a thin-walled portion having a gently changing plate thickness. The metal thickness of the thinnest part needs to be ½ or less, preferably ⅓ or less of the processed thickness in terms of can openability. This process determines the breaking position when opening the can, but in order to improve the can openability and make the shape of the opening piece after opening the can desirable, the opening piece that is extruded upward or downward is set to the previous level. It is possible to perform processing that pushes back to a position close to. The pushed back shape is shown in FIG. The depth of the cutting guide groove, the thickness of the thinnest part, and the like can be set to a required value according to the workability of the material by setting the processing conditions as required. The processing conditions are selected according to

Further, according to the method of the present invention, since the basic working is press working such as extrusion or pushback by shoulder radius portions having mutually convex smooth surfaces, a tool found in the sharp blade pressing system. Life issues are reduced and excellent productivity is guaranteed. The present invention is mainly characterized by optimizing the cutting guide groove existing in the peripheral portion of the opening piece.The tear-off method in which the handle and the opening piece are torn off from the can body, and the handle and the opening piece are opened. The present invention can be applied to both the Stein-tab type that remains fixed to the can body even after the can.

Examples will be described below. Steel having the components shown in Table 1 was melted in a vacuum melting furnace to obtain a steel ingot.
After soaking these steel ingots at 1150 ° C for 1 hr, plate thickness 30m
It was roughly rolled to m, heated again at 1150 ° C. for 1 hr, and hot-rolled to a plate thickness of 3.0 mm. After pickling these hot rolled plates,
After recrystallization annealing under the conditions shown in Table 2, temper rolling or 2CR was performed. The parameters of the annealing conditions in Table 2 are shown in FIG.
Shown in After that, electroplating was performed with a coating amount of the lid steel plate of ^{2 to 3} g / m ² , and then tin was reflow-treated and then chromate-treated. The steel sheet was reheated to bond the resin coatings shown in Table 3 on both sides.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

A tensile test was conducted on the steel sheet thus prepared. Further, a formed steel sheet was used to mold a Stein tab type lid having a lid diameter of 66 mm, and a corrosion resistance test and a can opening test were conducted. For corrosion resistance, visually observe the state of rust generation after leaving it in the atmosphere stored at 35 ° C for 3 months and pass it if there is no rust in the cutting guide groove, pass if there is any rust. And

The can openability is measured by measuring the can open force when the can is opened.
The opening force at initial breaking (POP) and the maximum opening force (Tear) after that were measured, and those loads which were below the commercially available aluminum Steion-tab type lid were accepted. Specifically, Tea with a POP of 2.0 kgf or less
If r was 2.4 kgf or less, it was determined to be acceptable. The angle θ of the tab at the time of initial breakage shown in FIG. 6 was measured, and those having a tab angle of 35 ° of commercially available aluminum were rejected. The results of these tests are shown in Table 4.

[0019]

[Table 4]

According to the first to third aspects of the present invention, no rust is generated in the cutting guide groove, the cutting guide groove has very good corrosion resistance, and it is not necessary to repair the coating in the cutting guide groove. Also, it has a good can openability as a lid. In No. 4 of the present invention, since the shoulder R of the die punch is too large and the cutting guide groove has a too gentle cross section, the can openability is unacceptable. On the contrary, in No. 5 of the present invention, the shoulder R of the die punch was too small, the resin film was cut, and the rust resistance was unacceptable. In the case of No. 6 of the present invention, since the resin film of the upper layer is as thick as 100 μm, the resin film peels off from the steel sheet, and the corrosion resistance is unacceptable.

Since the film thickness of 7 other than the present invention is too thin, the corrosion resistance is unacceptable. Also, since the TS is large, the can openability is also unacceptable. Since 8 outside the present invention has a large n value, the tab angle becomes too large and is rejected. In the case of 9 other than the present invention, since the TS is too large, the breaking strength becomes too large, and the tab angle also fails.

[0022]

According to the present invention, if an easily openable lid made of a steel plate is put into practical use, a steel monometal can can be used for both the easily openable lid and the body. It is possible to provide products suitable for the market to the market.

[Brief description of drawings]

FIG. 1 is a sectional view of a cutting guide surface that has been pressed.

FIG. 2 is a cross-sectional view of a cutting guide surface after push-back processing of the present invention,

FIG. 3 is a diagram showing parameters of annealing conditions,

FIG. 4 is a view of a conventional easy-open can lid,

FIG. 5 is a view showing a cutting guide groove having a V-shaped cross section,

FIG. 6 is a view showing the easy-open can lid in a state in which the tab is in a standing state,

FIG. 7 is a view showing the easily openable lid in a state where the angle φ of the opening piece is small.

[Explanation of symbols]

 1 Lid body 2 Opening piece 3 Cutting guide groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ito 1-1 Tobahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Inside Nippon Steel Co., Ltd. Yawata Works (72) Inventor Hiroshi Nishida Tobata-ku, Tobata-ku, Kitakyushu, Fukuoka No. 1 town No. 1 Nippon Steel Corporation Yawata Works

Claims (2)

[Claims] 1. A thickness of 10 μm to 100 μm and an elongation at break 1
It has a resin film of more than 00% and TS is 46k at the nominal stress.
gf / mm ² or less, a steel sheet having an n value of 0.15 or less,
The cutting guide groove forming die forming the opening piece shape has a shoulder radius of 0.1 mm to 1.6 mm and a clearance of -1.6.
Using a metal mold with a diameter of 0.3 mm to 0.3 mm, the plate is pressed and formed with the shoulder radii of the upper and lower molds, and the metal thickness of the thinnest part is reduced to 1/2 or less of the metal thickness before processing. A method for manufacturing an easily openable lid, characterized by forming a guide groove. 2. A thickness of 10 μm to 100 μm and an elongation at break 1
It has a resin film of more than 00% and TS is 46k at the nominal stress.
An easily openable lid that does not require repair coating using a steel sheet having a gf / mm ² or less and an n value of 0.15 or less.