Abstract: A hot press-forming method includes a forming step that clamps a steel sheet heated to a temperature not less than an austenite transformation temperature and press-forms the steel sheet into a desired shape by causing a forming concave of a die and a convex of a punch to be close to each other. A formed portion has side and top portions that merge. The side portion rises up from an inner circumferential edge of a flange portion having been clamped by the die and the blank holder. A cooling step cools a region of the steel sheet after the heating step has been completed and before the forming step is completed. The particular region is along an inter-edge area formed between an opening circumferential edge of the forming concave and a top circumferential edge of the forming convex before the forming step is completed.

Abstract: A hot press-forming method includes a forming step that clamps a steel sheet heated to a temperature not less than an austenite transformation temperature and press-forms the steel sheet into a desired shape by causing a forming concave of a die and a convex of a punch to be close to each other. A formed portion has side and top portions that merge. The side portion rises up from an inner circumferential edge of a flange portion having been clamped by the die and the blank holder. A cooling step cools a region of the steel sheet after the heating step has been completed and before the forming step is completed. The particular region is along an inter-edge area formed between an opening circumferential edge of the forming concave and a top circumferential edge of the forming convex before the forming step is completed.

Abstract: A sheet forming method including the steps of: holding a blank between a blank holder and an opposing die so that wrinkling is prevented in the blank; and forming the blank to an objective shape with a punch, while imposing a force of a variable bead on the blank at a selected position in a point manner and only during a part of the entire forming period selectively. An apparatus for conducting the above method.

Abstract: An inexpensive process for making a minute circular hole having a smooth peripheral edge in a thin wall of a metal article. A depression is formed on one surface of the wall so as to simultaneously form a projection on the other surface thereof. The apex of the projection is positioned in a spaced relationship to a cathode in an electrolyte. An electric current is then introduced between the projection, which serves as an anode, and the cathode, which acts to selectively and anodically dissolve the apex of the projection so as to form a minute hole in the wall.