Verfahren zur Trichterformgebung im Hinblick auf Fertigung von Kolben und zu deren Durchführung angemessene Vorrichtung

摘要

It is an object of the present invention to reduce variations in dimensional accuracy such as the outer-diameter accuracy and roundness of a flare shape and the concentricity between the bulb portion and the flare portion. According to the present invention, a lower mold (1) formed of a metallic material and forming a recess flare shape (1a) that is subjected to surface treatment forms a flare shape (21b) almost identical to the flare shape (1a) by means of the rotational motion of a rotating head portion (2). An upper mold (10) is fitted in the lower mold (1) to form a flare-shaped gap portion (13), into which glass is forced to form a flare shape (22).