Compression molding press with hydraulic controls

摘要

Predominately hydraulic controls with an optional electrical feedback loop for a compression molding press is provided for a press having the main force provided by four hydraulic cylinders one at each corner of the ram and a fifth cylinder at its center. A hydromechanical servo valve at each corner of the press each in conjunction with a position gauge rod controls the adjacent cylinder to keep the ram parallel with the bed and an averaging valve applies the average pressure of the corner cylinders to the central cylinder. A servo controlled position motor synchronously moves each of the hydromechanical valves with respect to the ram to affect position and velocity control of the ram. A force comparator samples the average cylinder pressure to establish a maximum pressure and to override the position control when that maximum pressure is approached. The electrical control senses the position of the servo controller to compare press position to a preset program and to control the servo accordingly.