| 摘要 |
The present invention provides a bellows device, which has superior durability respective to a repeatedly expanding operation. The bellows device comprises: a first convex crease line (R1); a second convex crease line (R2), which is linearly and continuously extended from a refraction point (a) of the first convex crease line (R1); a third convex crease line (R3), which connects neighboring refraction points with each other; a first concave crease line (V1), which is formed in parallel between the first convex crease lines and is connected to the center point (c) of the third convex crease line (R3); a second concave crease line (V2) formed in parallel between the second convex crease lines (R2); a fourth convex crease line (R4), which is formed from an approaching end (b) of the second concave crease line (V2) to the center point (c) of the third convex crease line (R3); a third concave crease line (V3); and a third concave crease line (V3), which is formed from the refraction point (a) to the approaching end (b) of the second concave crease line (V2). A folded part (12), which is surrounded by the third convex crease line (R3), the fourth convex crease line (R4), and the third concave crease line (V3), is folded and put into a second surface crease box part (10S). Also, the length of the fourth convex crease line (R4) is set to be longer than the length of the third convex crease line (R3). |
