JPS61289933A - Scoring method for easy opening can cover - Google Patents

Abstract

PURPOSE:To prevent a crack generation in scoring and to increase the opening as well by reducing the thickness of the prearranged place for opening of the plate to be worked and by notching a score on the reduced flat part thereof. CONSTITUTION:The opening prearranging place of the plate 1 to be worked for easy opening can cover is subjected to 15-45% pressure reducing by using the trapezoidal tool 2 having a flat cross section and plane tool 3. With this primary work the flat part 1-1 having a certain width is formed. Inside this flat part 1-1 a score is notched by the punch 4 with its tip sharply projecting. The opening force becomes smaller due to the sectional area being small on the scoe peripheral part thereof. The stress concentration onto the score tip corner part becomes smaller therefore in scoring and the generation of a crack is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for scoring easy-open cans.

(Prior art) Easy-open cans are used for beer cans, carbonated beverage cans, juice cans, etc., which have a score engraved on the can lid in advance and can be opened without a single tool such as a can opener. .

The ease with which this easy-open can lid can be opened is as follows:
Score processing is one of the major factors.

It is known that the openability can be improved by making the residual thickness after score processing as thin as possible, but with the current score processing technology, it is inevitable that variations in the score residual thickness will occur. For example, if the score processing is increased to make the remaining thickness as thin as possible, cracks may occur at the bottom corners of the score, or the strength may decrease significantly in some areas, causing the problem that the material cannot withstand the internal pressure of the can. arise.

Studies have been conducted to facilitate the opening of easy-open can lids, and several scoring methods have been proposed. For example, in JP-A-54-54788, after the opening score and the auxiliary score are engraved, a circumferential bead is provided along the opening score to create a constriction in the opening score and improve the opening property. , Japanese Patent Publication No. 57-175
In 034, a concave seat is provided as a downward I-tapered surface, a lower die is provided with a protrusion on the periphery of the upper surface of the concave seat, and an upper die is provided with a tapered surface facing the downward tapered surface and a flat protrusion. Press the thin plate into a concave shape to thin the thin plate portion in contact with the tapered surface by the action of the tapered surface, and form a biting groove with the protrusion, and then press it into a flat plate shape to thin the thinned portion. It has been proposed to bend the material into a V-shape and form a cutting guide groove to facilitate opening.

(Problems to be Solved by the Invention) As a result of these studies, the opening properties of easy-open can lids have been improved, making them easier to open.

However, this is not completely satisfactory, and furthermore,
It is necessary to make it easier to open.

Furthermore, when score processing is performed, it is important that the processing method is such that cracks do not occur even if the remaining thickness is reduced, and it is desirable that the processing method be easy.

The present invention provides a scoring method for an easy-open can lid that has good opening properties and does not cause cracks during scoring even if the remaining thickness is made as thin as possible.

(Means for Solving the Problems) The present inventor focused on the fact that the aperture acts through the periphery of the score, and that the aperture property is greatly influenced by the state of the periphery of the score, and found that the cross-sectional area of the periphery of the score decreases. We succeeded in manufacturing easy-open can lids using work hardening.

The gist is that in score processing of easy-open can lids, the intended opening location on the workpiece plate is cut in one place using a tool with a flat part.
The easy-open can score scoring method is characterized by performing primary processing to reduce the thickness by 5 to 45%, and then carving a score on the primary processed flat part.

The present invention will be explained in detail below with reference to the drawings.

In the drawings, reference numeral 1 denotes a plate to be processed, which is a thin plate to be processed into an easy-open can lid. A score is engraved on the workpiece plate l, but first tools with a flat cross section, for example, trapezoidal tool 2 and flat tool 3, or trapezoidal tool 2 and flat tool 3, are used.
A team of comrades perform a primary process to reduce the thickness of the planned opening area of the plate 1 by 15 to 45%. It is preferable that a flat portion 1-1 with a certain width is formed at the location where the primary processing is performed.

The reason why the primary processing is 15 to 45% is as follows.

In other words, if the reduction in plate thickness is small, the pop value (p
OP value) becomes large and a large force is required to open the opening, so processing is performed at 15% or more.

On the other hand, when this machining rate becomes large, the plate thickness t of the flat portion 1-1 at the part where the plate thickness is reduced is formed in the primary processing.

Then, the difference between the plate thickness t2 of the score-processed part becomes smaller, and stress concentration on the score-processed part at the time of opening becomes weaker, resulting in poor can opening performance. Therefore, the upper limit of primary processing needs to be 45%.

Next, using a punch 4 with a sharply protruding tip, a score is engraved within the flat portion 1-1 where the primary processing has been performed. The board thickness around the engraved score is thin due to the primary processing, and therefore the cross-sectional area around the score is small. Since the opening is performed through the periphery of the score with a small cross-sectional area, the opening force is further reduced by this method, and the score processing is performed after the stress is once dispersed by the primary processing, so the degree of processing is also reduced. Therefore, when performing the score processing, stress concentration at the corner of the tip of the score becomes smaller than when no primary processing is performed, resulting in the effect of making it difficult for score cracks to occur. That is, no cracks occur even if the remaining score thickness is made as thin as possible.

(Example) Next, examples will be shown.

Weight Z Te, C: 0.04%, Si: 0. O
IX, Mn: 0.20%, S: 0.010
X, P: 0.011%, Al: 0.042
After continuous casting, a slab containing X, N: 0.0031% was hot-rolled to a thickness of 2.3 mm at a finishing temperature of 885°C and a winding temperature of 6!0°C. After descaling, it was cold rolled to a thickness of 0.24 mm, and then continuously annealed at 700° C. for 30 seconds. The hardness of the steel plate after continuous annealing is 8 at H123oT.
It was 0.

The steel plate is subjected to primary processing under the conditions shown in Table 1, and then
Score remaining thickness 55p with a protrusion punch in the next processed area
We processed the score to match. Then, measure the can opening force,
The pop values are shown in Table 1.

Table 1 (Effects of the Invention) As is clear from this result, according to the present invention, the pop value is low and opening becomes very easy. In addition, even if the remaining thickness is reduced during score processing, there is also the effect that cracks are less likely to occur.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of primary processing according to the present invention. FIG. 2 is a diagram showing one embodiment of score processing according to the present invention. ■... Work plate, 1-1... Flat part, 2... Trapezoidal tool, 3... Flat tool, 4... Punch.

Claims (1)

[Claims] In score processing of easy-open can lids, the intended opening location on the workpiece plate is scored with a processing tool having a flat cross section.
A method for scoring an easy-open can lid, which comprises performing primary processing to reduce the thickness by 45%, and then carving a score in the primary processed area.