Abstract: A doctor blade head for coating a transfer roller includes a semi-cylindrical cavity to enable streamline fluid flow therethrough, and check plates at the inlet and outlet openings for permitting unidirectional flow into the inlet opening from said pump and out of the outlet opening toward the pump. An hydraulic accumulator acts as a fluid pressure and fluid velocity balancing device, and includes a rolling diaphragm piston moving in a cylinder that is connected to the inlet fluid path, with a spring impinging on the piston to absorb pressure surges and compensate pressure dropoffs.

Abstract: A chambered doctor blade apparatus provides an automatic system for cleanup and replacement of ink or coating substance, as well as operating a hydraulic head loading system that includes hydrostatic compensation, and integrates the head loading mechanism into the automated cleaning, flushing and replacement cycle. A supply pump, a return pump, and a plurality of lines are connected by electrically operated valves. A programmable logic controller (PLC) is connected through a display driver to a touch screen display that presents an interactive graphical user interface for control purposes. The PLC is programmed to carry out sequentially the required steps for cleaning, refilling, and running the chambered doctor blade assembly. The PLC is connected to each of the pumps and valves, and to the head loading valve of a hydrostatically compensated hydraulic head loading system.