| 摘要 |
PURPOSE:To provide a square-shaped cover which can be manufactured continuously and mechanically and is suitable for an object with a slope surface as well, by a method wherein oblique sides are formed by cutting four corners of a rectangular sheet, having heat-sealing properties, in a manner to place the corners at an angle, and sides of a trapezoidal sheet are heat-sealed to aforesaid sides. CONSTITUTION:Oblique sides 2, 21, 3, and 31 are formed by cutting four corners of a rectangular sheet 1, having heat seal properties, in a manner to place the four corners at an appropriate angle of 30-60 deg., so that an appropriate width or no width is created at the center part of the sheet 1. Sides of a trapezoidal sheet 8, which has heat-sealing properties and the equal sides to the oblique sides 2, 21, 3, and 31 and sides 6, 7 joined to said oblique sides, are heat-sealed (h and h1) to said oblique sides and the sides connected to said oblique sides to form a square-shaped cover. |
