US 4,362,037 A · Hollow article internal pressure forming apparatus and method

Abstract

An upper die is movable by a ram downwardly against a lower die with the dies enclosing a hollow article such as a knobshell in die cavities thereof. RAM continued downward movement of the closed dies forces a piston connected to the lower die downwardly against hydraulic fluid of a containing cylinder forcing the hydraulic fluid internally of the knobshell through the neck thereof forming the knobshell outwardly against the die cavity surfaces. The piston size compared to the knobshell size automatically creates a reactive force reversely tending to maintain the dies closed greater than the internal knobshell forming force tending to separate the dies. After knobshell forming, reverse ram movement first relieves piston pressure against the hydraulic fluid and ultimately separates the dies with a knockout member being actuated to eject the formed knobshell. During forming, an automatic pressure relief valve maintains maximum hydraulic fluid pressure not exceeding a predetermined maximum pressure and an automatic fluid refill valve refills the cylinder with hydraulic fluid at separation of the dies for formed knobshell removal.

Claims25

Dependent claims

In a forming apparatus for bulging hollow bulbous metal knobshells outwardly relatively small distances against enclosing die cavity surfaces by application of only internal high fluid pressures directed solely through a preformed reduced size knobshell neck access opening;

the apparatus including:
first and second dies constructed and arranged with said dies movable longitudinally together to a closed position and thereafter in said closed position by continued longitudinal urging placing said dies in progressive longitudinal pressure exerting conditions, said dies in said closed position forming a die cavity having surfaces enclosing said knobshell with a reduced size knobshell neck access opening exposed to said first die, said die cavity surfaces outwardly of said knobshell being exposed at all times venting to the atmosphere;
die moving means for moving said dies to and from said closed position and progressively urging said dies into said die longitudinal pressure exerting conditions only while in said closed position;
fluid pressure means operably connected free of reaction until said dies are in closed position but directly fluid flow reactive to said dies being urged into said die progressive longitudinal pressure exerting conditions and operably connected to said first die directing fluid flow into said knobshell through said knobshell neck access opening, said fluid pressure means during said dies being urged into said progressive longitudinal pressure exerting conditions at all times exerting a greater reverse longitudinal force on said dies tending to retain said dies in closed position than knobshell forming force created internally outwardly from within said knobshell against said die cavity surfaces tending to urge said dies apart.

1 more element

In a method of bulging hollow bulbous metal knobshells outwardly relatively small distances against enclosing die cavity surfaces by application of only internal high fluid pressures directed solely through a preformed reduced size knobshell neck access opening;

the steps of:
applying a die moving force longitudinally against a first die to move and maintain said first die and a second die together in closed position enclosing a hollow bulbous metal knobshell within a die cavity surrounded by die cavity surfaces;
maintaining said die cavity surfaces outwardly of said knobshell at all times venting to the atmosphere;
continuing to urge said first die longitudinally while in said closed position by said die moving force;
opposing said die moving force urging in said die closed position which opposition will tend to maintain said dies in said closed position by a reactive force resulting from and causing fluid to be forced to flow by said die moving force continued die urging internally of said knobshell through a preformed reduced size knobshell neck access opening creating a forming force tending to separate said dies while fluid pressure forming said knobshell outwardly against said die cavity surfaces;
maintaining at all times said reactive force tending to maintain said dies in said closed position greater than said knobshell internal forming force tending to separate said dies.

3 more elements

Dependencies are inferred from the claim text.

Hollow article internal pressure forming apparatus and method

Life of this patent

Hollow article internal pressure forming apparatus and method

Life of this patent

Abstract

Claims25