Patent ID: 6877977
Filing Date: 2005-04-12
Classification: B29C

Abstract:
1. A two-platen closing unit for an injection molding machine comprising: a fixed mold mounting plate; a moving mold mounting plate; a plurality of columns received in the moving mold mounting plate and traversing the fixed mold mounting plate, each said column slidingly supported in the fixed mold mounting plate and having a clamping plunger received in a clamping cylinder, thereby defining a clamping pressure compartment, whereby the clamping pressure compartments in the clamping cylinders are in hydraulic communication with one another, wherein a first plurality of clamping plungers is configured as a dual-action plunger which divides the clamping cylinder into the clamping pressure compartment and an opening pressure compartment and includes a flow passage for connecting the clamping pressure compartment with the opening pressure compartment; a spindle drive coupled to a second plurality of clamping plungers and having spindles connected in driving relationship with a hydraulic piston and cylinder drive for feeding a hydraulic pressure medium into the clamping pressure compartments of the second plurality of clamping plungers, wherein the hydraulic piston and cylinder drive defines a pressure compartment; a flow control valve disposed in the flow passage and including a stem-like valve body which closes the flow passage in a first operative position and clears the flow passage in a second operative position; a pilot valve interacting with the valve body to control the first and second positions of the valve body; a shut-off connection line for fluidly connecting the pressure compartment of each spindle drive with the clamping pressure compartments, and a pressure source connected to the opening compartments for ensuring a minimum pressure.