| 摘要 |
PURPOSE:To improve easiness of opening a can lid by a method wherein an angle formed by a line between an starting end and a fixed portion of a bead has a certain angle with respect to the torn direction, reducing a force required for tearing the lid. CONSTITUTION:An opening score 2 is engraved along a periphery of a can lid 1, and a fixed portion 4 containing a pull ring 1 fixed on the lid 1 is located in the vicinity of a part of the score 2. A pair of beads 5 are formed on the both sides of the fixed portion 4, which are symmetric with respect to an axis Y-Y parallel to a torn direction X. A line 1 connecting an end 5a of the bead 5 and a tip 10 of the fixed portion 4 has an angle theta of 45 deg.-85 deg.. As theta increases, an initial force required to pull up the pull ring 3 and tear the lid, especially a force to tear from an intersection 2b to 2c decreases. However, the angle is 85 deg. or larger, the lid is likely to bend above the beads 5 and cannot be opened deeply toward the torn direction on the initial stage of opening, failing in decreasing the force. On the other hand, when theta is less than 45 deg., not only the initial force required increases but also the force for opening the lid at a beginning point 2a increases. |
