Abstract: An apparatus is described that converts a manual adjustment procedure of a lathe on an existing pulp-grinding machine into an automated electronic procedure. The pre-existing lathe has a sharpening burr affixed to a movable plunger. The plunger is manually lowered by a hand crank until the burr contacts a surface of a pulp-grinding stone. The present invention replaces the hand crank with a reversible, variable speed motor. A transducer is affixed to the plunger wherein electric signals are produced in response to vibrations resulting from contact between the burr and the grinding stone. The signals are processed by a standard programmable controller to control the motor. An electronic encoder electrically measures the position of the plunger and communicates the position to the programmable controller. When the burr on the plunger contacts the grinding stone, the motor is programmed to automatically stop.

Abstract: A novel retrofit process for converting the hydraulic lathe of an existing pulp-grinding machine into the new electric one is described. This process includes utilization of the pre-existing hydraulic cylinder as a supporting housing and shield for a major portion of the drive assembly for the electric lathe. In the preferred "retrofit" embodiment, the drive for the lathe comprises a ball-screw assembly housed inside the cylinder, after the cylinder has first been evacuated. This drive assembly includes a longitudinally fixed, but rotatable "power screw" that is supported by opposite ends of the cylinder. A variable speed, reversible motor is located outside one of the cylinder ends and is coupled to the screw to selectively rotate it. A threaded collar is located inside the cylinder and straddles the screw. It carries a pair of parallel, spaced rods that extend through the end of the cylinder that is opposite the cylinder's "motor end".