Airbag cover

An airbag cover comprising:

• a single-layered cover material formed from a synthetic resin material by molding having a lid portion which is opened to form a projection opening through which an airbag projects and a thin breakable portion defines the lid portion to be broken by a pressure of the inflating airbag, and formed,
• a part of the breakable portion which lies on a distal edge of the lid portion which lies away from a hinge portion of the lid portion when the lid portion is opened and where the breakable portion is provided being formed into a distal edge straight section which is provided in the shape of a straight line,
• the distal edge straight section being formed through cutting operation in which a working tool is moved over a rear surface of the cover material after the cover material has been molded so as to form a notch therein by a cutting blade of the working tool,
• wherein the distal edge straight section is formed by providing discontinuously a thick portion whose thickness is made to fall in the range of 1.0 to 1.6 mm and a thin portion whose thickness is made to fall in the range of 0.6 to 1.0 mm so as to be thinner than the thick portion within a working area whose thickness is set to range from 2.0 to 3.0 mm, and
• wherein, in a sectional area change curve marked by plotting distal edge section values of sectional areas taken in 50 mm segments along the distal edge straight section,
• the thick portion and the thin portion are formed so that a maximum change rate, which is a rate of difference between a maximum of the distal edge section values and a minimum of the distal edge section values based on the maximum, is made to be 15% or more, without providing an area where the distal edge section values of the sectional areas decrease from a center of the sectional area change curve towards both ends thereof, as a range where the distal edge section values of the sectional areas are larger than the minimum distal edge section value.