Abstract: A pipe-tapered-thread machining tap has a thread, four spiral flutes and four cutting edges that include a plurality of thread intersection portions at each of which a corresponding one of the four cutting edges intersects with the thread. The thread intersection portions of the cutting edges have four groups, such that each of the four groups has ones of the thread intersection portions that are portions of a corresponding one of the four cutting edges. Every two of the thread intersection portions of each of the four groups is removed, such that, in each of the four groups, at least one of the thread intersection portions that is removed and at least another one of the thread intersection portions that is not removed are alternately arranged in a direction in which a corresponding one of the four cutting edges extends.

Abstract: A pipe-tapered-thread machining tap has a thread, four spiral flutes and four cutting edges that include a plurality of thread intersection portions at each of which a corresponding one of the four cutting edges intersects with the thread. The thread intersection portions of the cutting edges have four groups, such that each of the four groups has ones of the thread intersection portions that are portions of a corresponding one of the four cutting edges. Every two of the thread intersection portions of each of the four groups is removed, such that, in each of the four groups, at least one of the thread intersection portions that is removed and at least another one of the thread intersection portions that is not removed are alternately arranged in a direction in which a corresponding one of the four cutting edges extends.

Abstract: Disclosed is a manufacturing method for molded glass articles including glass optical elements such as high precision lenses not requiring grinding and polishing after press molding. The manufacturing method according to the invention is a method for manufacturing the molded glass articles having a higher surface precision with a high productivity by pressing a glass material in a stepwise manner constituted of some steps depending on a temperature condition of the glass material.

Abstract: A manufacturing method for molded glass articles including glass optical elements such as high precision lenses not requiring grinding and polishing after press molding. The manufacturing method according to the invention is a method for manufacturing the molded glass articles having a higher surface precision with a high productivity by pressing a glass material in a stepwise manner constituted of some steps depending on a temperature condition of the glass material.