Hydraulic pressure control apparatus

Claim 2

In a machine, a first member movable in one direction along a path, hydraulic cushion means adapted to provide a yieldable opposing force to said member during a portion of its movement along said path, a hydraulic pressure supply for supplying hydraulic pressure to said hydraulic cushion means for creating the yieldable opposing force, expansion chamber means defining an expansion chamber connected in fluid communication with said hydraulic cushion means, and actuating means for expanding said chamber to completely remove the hydraulic pressure from said hydraulic cushion means after said first member has moved through a predetermined portion of said path, said actuating means including means for expanding said chamber at a rate sufficient to reduce the hydraulic pressure in said hydraulic cushion means to a pressure which is equal to or less than ambient pressure.

Claim 3

In a machine having pressure pad means for supporting material and a first member for shaping the material supported on said pressure pad means, hydraulic cushion means yieldably opposing movement of said pressure pad means in the one direction by hydraulic pressure from a hydraulic pressure supply, said first member upon movement effecting movement of said pressure pad means during shaping of the material, and pressure control means for instantaneously and completely relieving the yieldably opposition of said hydraulic cushion means, said pressure control means including expansion chamber means connected by passageways to said hydraulic cushion means and expandable after said first member moves through a predetermined portion of the work stroke to provide an increase in volume greater than the volume of fluid displaced by said hydraulic cushion means during movement of said pressure pad means such that the yieldable opposition by said hydraulic cushion means is completely relieved.

Claim 4

In a machine having pressure pad means for supporting material and a first member for shaping the material supported on said pressure pad means, hydraulic cushion means yieldably opposing movement of said pressure pad means in the one direction by hydraulic pressure from a hydraulic pressure supply, said first member upon movement effecting movement of said pressure pad means during shaping of the material, and pressure control means for instantaneously and completely relieving the yieldably opposition of said hydraulic cushion means, said pressure control means including expansion chamber means connected by passageways to said hydraulic cushion means and expandable after said first member moves through a predetermined portion of the work stroke to provide an increase in volume greater than the volume of fluid displaced by said hydraulic cushion means during movement of said pressure pad means such that the yieldable opposition by said hydraulic cushion means is completely relieved.

Claim 7

In a machine as defined in claim 1 wherein said hydraulic cushion means includes at least one cushion chamber adapted to receive hydraulic fluid under pressure, said one cushion chamber having a volume dependent on the position of said first member along said path, said expansion chamber means including a movable wall portion to vary the volume of said expansion chamber, said one cushion chamber being connected to said expansion chamber by passageways therebetween, said expansion chamber being expanded at a rate greater than the rate of contraction of the volume of said one cushion chamber on movement of said first member through said predetermined portion of said path such that the yieldable opposition by said hydraulic cushion means is completely relieved and the hydraulic pressure in said hydraulic cushion means is reduced to a pressure which is below ambient pressure.

Claim 8

In a machine as defined in claim 1 having means providing a passageway connecting said hydraulic pressure supply to said hydraulic cushion means, said passageway being restricted after movement of said member through said predetermined portion of said path.

Claim 9

In a machine as defined in claim 5 having a passageway connecting said hydraulic pressure supply to said hydraulic cushion means, and further comprising pressure control means for blocking said passageway after movement of said first member through said predetermined portion of said path to disconnect the hydraulic pressure supply from said hydraulic cushion means.

Claim 10

In a machine as defined in claim 1 wherein said expansion chamber is expanded at a rate such that said hydraulic cushion means is urged in the direction opposite to said one direction.

Claim 11

A machine as defined in claim 4 wherein said passageways are defined by at least one substantially rigid body such that the volume of said passageways remains substantially constant upon removal of fluid pressure to allow a substantially instantaneous pressure release of the hydraulic pressure in said one hydraulic cushion means.

Claim 12

In a machine as defined in claim 4 wherein a fluid chamber consists of said one cushion chamber, passageways connecting said one cushion chamber to said expansion chamber, said fluid chamber having an increasing volume after movement of said upper die portion through the predetermined portion of said path such that the yieldable urging of said pressure pad means in a direction opposite to the movement of said upper die portion is completely removed at the predetermined distance.

Claim 13

In a machine as defined in claim 2 having a pressure passageway from said hydraulic pressure supply to said hydraulic cushion means, said pressure control means restricting said pressure passageway upon movement of said first member through a predetermined portion of the work stroke.

Claim 14

In a machine as defined in claim 2 wherein said pressure control means includes means to disconnect the hydraulic pressure supply from said hydraulic cushion means upon movement of said movable die portion through the predetermined portion of the work stroke.

Claim 15

In a machine as defined in claim 2 and including pressure control means having means defining a pressure passageway therethrough connecting the hydraulic pressure supply with said hydraulic cushion means and a piston movable upon movement of said first member Through said predetermined portion of said work stroke to block the pressure passageway in response to movement of said first member to disconnect said hydraulic pressure supply from said hydraulic cushion means.

Claim 16

In a machine as defined in claim 2 wherein said pressure control means includes a piston, a floating piston, a pressure passageway connecting the hydraulic pressure supply with said hydraulic cushion means, a body having an aperture therein adapted to receive said piston and said floating piston, said floating piston defining a portion of said pressure passageway, said expansion chamber having a movable wall portion consisting of a portion of said piston, said piston operable from one position in response to movement of said first member through the predetermined portion of the work stroke to block said pressure passageway and operable to provide for the expansion of said expansion chamber from its original volume to receive the fluid displaced by said hydraulic cushion means.

Claim 17

In a machine as defined in claim 13 wherein said piston is adapted to block said pressure passageway portion defined by said floating piston at a contact position in response to movement of said first member through the predetermined portion of the work stroke, said piston and said floating piston remaining in contact throughout the remainder of the work stroke of said first member such that the hydraulic pressure supply remains disconnected from said hydraulic cushion means through the remainder of the work stroke.

Claim 18

In a machine as defined in claim 14 wherein said pressure control means includes biasing means to return said floating piston to said contact position during the upward stroke of said first member.

Claim 19

In a machine as defined in claim 13 wherein said piston is returned to said one position by the hydraulic pressure from said hydraulic pressure supply during the upward stroke of said first member such that the volume of said expansion chamber returns to a volume less than said original volume such that said pressure passageway is no longer blocked by said piston.

Claim 20

In a machine as defined in claim 13 wherein said pressure pad means includes a plurality of pressure pads, said hydraulic cushion means including a corresponding plurality of hydraulic cushions, said pressure control means including a corresponding plurality of pressure control devices, each of said corresponding hydraulic cushions connected to one of said corresponding pressure control devices and its corresponding pressure pad means.

Claim 21

In a machine as defined in claim 13 wherein said pressure pad means includes a first and a second part, said hydraulic cushion means having housing means including a base member having apertures therein, hydraulic plungers adapted to be slidably received by said apertures of said housing means, at least one portion of said hydraulic plungers having one end thereof in contact with said first part of said pressure pad means and at least another portion of said hydraulic plungers having one end thereof in contact with said second part of said pressure pad means, said housing means having a first and second annular groove therein, said pressure control means including a first pressure control device connected to said first annular groove and a second pressure control device connected to said second annular groove, said first pressure control device adapted to actuate in response to movement of said first member through a first predetermined portion of the work stroke and said second pressure control device adapted to actuate in response to movement of said upper die portion through a second predetermined portion of the work stroke.

Claim 22

In a machine as defined in claim 2 wherein said hydraulic cushion means includes plunger means, and a hydraulic cushion body having at least one aperture therein adapted to receive said plunger means, said plunger means adapted to have fluid pressure acting on one end portion thereof to provide for said yieldable oppoSition.

Claim 23

A method for forming material as defined in claim 3 which includes restricting said pressure passage upon movement of said pressure pad through a predetermined portion of its work stroke.

Claim 24

A method for forming material as defined in claim 20 in which restricting said pressure passage includes blocking said pressure passage such that the hydraulic pressure supply is disconnected from said hydraulic cushion means.

Claim 25

A method for forming material as defined in claim 3 in which expanding said expansion chamber includes expanding the volume of said expansion chamber at a rate greater than the rate of volume displaced by said hydraulic cushion means such that the yieldable opposition to movement of said pressure pad means is completely removed.