Press for hot hydrostatic extrusion

Claim 2

Press for hydrostatic extrusion comprising a press stand, a pressure chamber comprising a high pressure cylinder axially displaceable in the press stand, a die engageable in the cylinder and a pressure-generating punch at the opposite end of the cylinder from the die which, when moved into the cylinder, generates a pressure in a pressure medium enclosed in the pressure chamber and surrounding a billet inserted in the chamber sufficient for extruding said billet through the die, a billet holder axially displaceable in the cylinder which divides the pressure chamber into first and second spaces and has valve means therein for creating a pressure difference between the spaces and permitting pressure medium to flow from the first space between the punch and the billet holder to the second space between the billet holder and the die at a certain pressure difference between the two spaces, which comprises means for selectively furnishing to the first space a pressure medium at a pressure below such pressure difference so that there is substantially no flow of the pressure medium past the billet holder, and thereafter at a pressure sufficient to cause flow of the pressure medium past the holder so that the second space is filled with pressure medium.

Claim 3

Press according to claim 1, in which the pressure medium source comprises a pump for pressure medium and a conduit connecting said source to first space of the pressure chamber, and at least one pressure-limiting overflow valve connected to said conduit between said first space in the pressure chamber and the pressure medium source.

Claim 4

Press according to claim 1, having two sources of pressure medium which deliver pressure medium under different pressures, and valve means for alternately connecting said sources to the first space in the pressure chamber.

Claim 5

Press according to claim 3, having a pressure-limiting overflow valve connected to the connection between said valve means and the pressure medium source delivering the least pressure.

Claim 6

Press according to claim 1, in which conduit connects said first space in the pressure chamber with the pressure-chamber source into a space at the end of the pressure chamber which is axially limited by a high-pressure seal between the pressure chamber and the punch and a seal within the second space in a part surrounding the pressure-generating punch.

Claim 7

Press according to claim 1, in which the second space in the pressure chamber between the piston and the die communicates during part of the opening period following extrusion with a pressure medium source from which the space is supplied with pressure medium to cool remnants of the billet and heated pressure medium.

Claim 8

Press for hydrostatic extrusion comprising a press stand, a high pressure cylinder having a pressure chamber therein, means mounting said higH pressure cylinder for movement longitudinally thereof within the press stand, said press stand having a pair of yokes at opposite ends, a die receiving member mounted on one of said yokes opposite the opening of the pressure diameter and having an extrusion passage therethrough, a die movable into a position opposite said die receiving member and having an opening therethrough adapted to be aligned with the opening in the die receiving member, said high pressure cylinder being movable a sufficient distance away from said die receiving member to permit the insertion of a die and a billet to be extruded therebetween, a pressure generating punch means on the opposite side of the pressure cylinder from the die receiving member mounted for movement within the high pressure cylinder, a billet holder mounted within said high pressure cylinder and axially movable therein, said billet holder dividing said pressure chamber into first space between the billet holder and the punch and a second space between the billet holder and the other end of the pressure chamber, said billet holder having valve means therein for preventing flow of pressure fluid from the first space to the second space when the pressure difference between the fluids in the first space and the s second space is less than a predetermined amount, means to move said high pressure cylinder towards said die receiving member to engage over a billet placed between the die and the high pressure cylinder, means for thereafter admitting fluid under pressure into said first space at a pressure lower than such predetermined pressure to move said billet holder towards the billet and thereby to force the die against the die receiving member, means for thereafter advancing the high pressure cylinder until it engages over the die, means for thereafter supplying fluid to said first space at a pressure greater than said predetermined pressure whereby to introduce pressure fluid into said second space around the billet, and means for thereafter moving said punch into the first space to increase the pressure therein and the pressure in said second space to extrusion pressure.

Claim 9

Press for hydrostatic extrusion comprising a press stand, a high pressure cylinder having a pressure chamber therein, means mounting said higH pressure cylinder for movement longitudinally thereof within the press stand, said press stand having a pair of yokes at opposite ends, a die receiving member mounted on one of said yokes opposite the opening of the pressure diameter and having an extrusion passage therethrough, a die movable into a position opposite said die receiving member and having an opening therethrough adapted to be aligned with the opening in the die receiving member, said high pressure cylinder being movable a sufficient distance away from said die receiving member to permit the insertion of a die and a billet to be extruded therebetween, a pressure generating punch means on the opposite side of the pressure cylinder from the die receiving member mounted for movement within the high pressure cylinder, a billet holder mounted within said high pressure cylinder and axially movable therein, said billet holder dividing said pressure chamber into first space between the billet holder and the punch and a second space between the billet holder and the other end of the pressure chamber, said billet holder having valve means therein for preventing flow of pressure fluid from the first space to the second space when the pressure difference between the fluids in the first space and the s second space is less than a predetermined amount, means to move said high pressure cylinder towards said die receiving member to engage over a billet placed between the die and the high pressure cylinder, means for thereafter admitting fluid under pressure into said first space at a pressure lower than such predetermined pressure to move said billet holder towards the billet and thereby to force the die against the die receiving member, means for thereafter advancing the high pressure cylinder until it engages over the die, means for thereafter supplying fluid to said first space at a pressure greater than said predetermined pressure whereby to introduce pressure fluid into said second space around the billet, and means for thereafter moving said punch into the first space to increase the pressure therein and the pressure in said second space to extrusion pressure.

Claim 10

In a press as claimed in claim 7, said means for admitting pressure fluid to said first space comprising a passage opening thereinto adjacent the end thereof into which the punch enters, said punch closing said passage when it is advanced to raise the pressure to extruding pressure.

Claim 11

A device as claimed in claim 7, said means for supplying pressure fluid comprising a first source of low pressure fluid and a second source of high pressure fluid and means for selectively connecting said first and second source to said passage.

Claim 12

In a press as claimed in claim 7, a passage opening into said pressure chamber edge the end thereof facing said die holding member, said die receiving member being sufficiently long to extend into said pressure chamber when the cylinder is moved to engage over the billet, said die receiving member extending into the high pressure cylinder to a sufficient degree to close said passage, and means to supply fluid pressure to said passage so as to introduce cool fluid into the second space when the high pressure cylinder is withdrawn from the die receiving member.