Abstract: A heat insulator is provided which can ensure satisfactory rigidity without increasing plate thickness. A number of convex portions are formed in an aluminum flat plate by embossing in an aligned state so that the flat plate part does not remain linearly between the convex portions. Each one convex portion has a hexagonal shape as viewed planarly, and the longitudinal section thereof, which includes vertices formed by opposing corners of the hexagonal shape, has a circular arc shape. The optimal value of convex height/convex width is a value in an experiment example, i.e., about 16.3% which is a value just before the start of blunting of the percentage performance improvement. From the viewpoint of a satisfactory percentage performance improvement, however, the convex height/convex width value is suitably not less than 12% and not more than 20.0%.

Abstract: A method for press-molding an embossed steel plate is able to cool even an embossed steel plate under conditions adequate for quenching. After a plate body with convex portions formed thereon is placed between an upper pressing die and a lower pressing die and the dies are closed, first and second circulation pumps are run to circulate cooling water.

Abstract: A method for press-molding an embossed steel plate is able to cool even an embossed steel plate under conditions adequate for quenching. After a plate body with convex portions formed thereon is placed between an upper pressing die and a lower pressing die and the dies are closed, first and second circulation pumps are run to circulate cooling water.

Abstract: A plate-like body is provided which can ensure satisfactory rigidity without increasing plate thickness. A number of convex portions are formed in an aluminum flat plate by embossing in an aligned state so that the flat plate part does not remain linearly between the convex portions. Each one convex portion has a hexagonal shape as viewed planarly, and the longitudinal section thereof, which includes vertices formed by opposing corners of the hexagonal shape, has a circular arc shape. The optimal value of convex height/convex width is a value in an experiment example, i.e., about 16.3% which is a value just before the start of blunting of the percentage performance improvement. From the viewpoint of a satisfactory percentage performance improvement, however, the convex height/convex width value is suitably not less than 12% and not more than 20.0%.