Patent ID: 6709260
Filing Date: 2004-03-23
Classification: B29C,F15B

Abstract:
A hydraulic press apparatus comprising:a lower plate; an upper plate adapted to be driven toward said lower plate via operation of a motion a position control device; a hollow cylinder under said lower plate, said hollow cylinder having an upper edge tightly engaged with a lower surface of said lower plate; a guide column connected to said upper plate, said guide column having a lower end portion that defines a rod for a first piston adapted to slide within said hollow cylinder, and said guide column defining an inner cylindrical cavity that extends through said first piston, with said inner cylindrical cavity being filled with hydraulic fluid; a hole extending through said lower plate, said hole being adapted to slidably accommodate said guide column; an aperture in a side surface of said hollow cylinder, said aperture allowing a volume defined between said lower plate and said first piston to communicate with a hydraulic device that is adapted to apply a hydraulic pressure within said volume when said first piston is in a lower position; a plunger piston adapted to slide within said inner cylindrical cavity, said plunger piston including an upper cylindrical portion that has a diameter such that said upper cylindrical portion is capable of plugging said inner cylindrical cavity, said plunger piston also including a lower portion that has a diameter smaller than said diameter of said upper cylindrical portion so as to prevent said lower portion from contacting walls defining said inner cylindrical cavity; and a through-bore allowing said inner cylindrical cavity to communicate with said volume when said upper cylindrical portion is at a level that is beneath a level of said through-bore.