초록 ▼

A hollow blank, such as a tube, is inserted in between two dies and is also received by two retractable die members. The interior of the blank is closed off, but working fluid is admitted to widen the blank. Widening is at first restricted to a central portion established by conical front faces of t

A hollow blank, such as a tube, is inserted in between two dies and is also received by two retractable die members. The interior of the blank is closed off, but working fluid is admitted to widen the blank. Widening is at first restricted to a central portion established by conical front faces of the die members. These members are retracted while continued application of fluid pressure progressively widens the blank, urging blank material into continued abutment with the front faces of the receding die members.

대표청구항 ▼

Machine for widening a tubular blank, comprising: a first and a second complementary die having cavity portions defining the widening; a pair of axially displaceable die elements, retractably positioned in the cavity portions, the die elements having particularly contoured front faces, facing each o

Machine for widening a tubular blank, comprising: a first and a second complementary die having cavity portions defining the widening; a pair of axially displaceable die elements, retractably positioned in the cavity portions, the die elements having particularly contoured front faces, facing each other in said die cavity, the tubular blank being inserted in the die elements inside said cavity; and a pair of plungers extending into the interior of the die elements and the tubular blank, at least one of the plungers having a bore for passage of pressurized fluid so that the blank is widened towards the particularly contoured front faces and the die cavity, and the widened portions extend axially in abutment with the receding die elements.