Package Machinery Co. Inc.

Robert E Farrell

The clamping preload in a molding machine or the like is set by adjusting the length of tie bars which support two die plates for opening and closing movement and a thrust plate. A clamping mechanism of given stroke is positioned between the thrust plate and one of the disc plates, and operates to close the die plates at one limit of the clamping stroke. With the clamping mechanism set at its limit and the tie bars set to establish a slight spacing between the die plates, the length of the tie bars is adjusted by means of a drive motor until the die plates are in contact without substantial preload. The clamping mechanism then opens the die plates and the drive motor is further energized to adjust the length of the tie bars and bring the die plates closer to one another by an amount corresponding to a preselected preload. The adjustment is measured from a high ratio mechanical drive connecting the drive motor to the adjustable tie bars, and the measured adjustment is compared with a desired adjustment corresponding to the preselected preload to deenergize the drive motor when the desired adjustment is reached.

Method and apparatus for setting a clamping load

The clamping preload in a molding machine or the like is set by adjusting the length of tie bars which support two die plates for opening and closing movement and a thrust plate. A clamping mechanism of given stroke is positioned between the thrust plate and one of the die plates, and operates to close the die plates at one limit of the clamping stroke. With the clamping mechanism set at its limit and the tie bars set to establish a slight spacing between the die plates, the length of the tie bars is adjusted by means of a drive motor until the die plates are in contact without substantial preload. The clamping mechanism then opens the die plates and the drive motor is further energized to adjust the length of the tie bars and bring the die plates closer to one another by an amount corresponding to a preselected preload. The adjustment is measured from a high ratio mechanical drive connecting the drive motor to the adjustable tie bars, and the measured adjustment is compared with a desired adjustment corresponding to the preselected preload to deenergize the drive motor when the desired adjustment is reached.

Apparatus for setting a clamping load

An injection molding machine having a ram for injecting a settable material into an associated mold includes a hydraulic actuator formed by a piston and cylinder assembly which displaces the ram during the injection operation. The piston is an unbalanced area piston which permits the ram to be displaced in both a regenerative and a nonregenerative feed mode. Fluid controls for operating the piston and cylinder assembly include a regeneration valve in fluid communication through the cylinder with opposite sides of the unbalanced piston to permit regenerative feed of the piston and ram in one valve position or to permit nonregenerative feed in another valve position. Displacing the ram in the regenerative or nonregenerative modes of operation allows the mold to be filled at different rates or pressures.

Injection molding machine with regenerative feed system

An injection molding machine has two stationary platens interconnected by tie bars and an immediate third platen which is movable on the tie bars. Separable mold portions are mounted respectively on one of the stationary platens and the third platen so that reciprocating movement of the third platen along the tie bars opens and closes the mold portions. A pair of toggle linkage mechanisms positioned at opposite sides of the machine and connecting with the movable third platen and one of the other platens are used to lockup the mold portions when the linkages assume their toggle positions. To move the toggle mechanisms into the toggle positions, a crosshead on slide rods connects with the mechanisms and is pushed away from the third platen at lockup by two piston and cylinder assemblies extending between the platen and the crosshead. The positioning of the cylinders and crosshead minimizes the overall length of the molding machine and permits mold lockup to be triggered more accurately.

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Springfield, MA, United States of America

Robert E Farrell