Patent ID: 8701948

Claim:
A method of aligning a stopper rod attached to a positioning and control apparatus with a nozzle disposed in the bottom of a molten metal holding reservoir where the positioning and control apparatus comprises: a lift apparatus centered on a substantially vertically oriented longitudinal axis, the lift apparatus having an inner tube telescopically mounted within an outer tube, the inner tube being reciprocally movable along the substantially vertically oriented longitudinal axis; a servomotor fixedly mounted at a lower end of the outer tube, the servomotor having a servomotor output interconnected to the inner tube whereby actuation of the servomotor results in reciprocal movement of the inner tube along the substantially vertically oriented longitudinal axis; a lower ring bearing having a lower ring bearing outer race and a lower ring bearing inner race, a vertically oriented central axis of the lower ring bearing offset from the substantially vertically oriented longitudinal axis, the lower ring bearing outer race fastened to a telescoping end of the inner tube by a lower ring bearing outer race mounting plate fastened to a slide angle plate to reciprocally move the lower ring bearing along the substantially vertically oriented longitudinal axis with the inner tube; an upper ring bearing having an upper ring bearing outer race and an upper ring bearing inner race, a vertically oriented central axis of the upper ring bearing offset from the substantially vertically oriented longitudinal axis and the vertically oriented central axis of the lower ring bearing; an adjustment plate respectively attached on opposing sides to the lower ring bearing inner race and the upper ring bearing outer race to rotate the upper ring bearing outer race with the lower ring bearing inner race; a locking plate attached to the upper ring bearing inner race to rotate the locking plate with the upper ring bearing inner race about the vertically oriented central axis of the upper ring bearing; a brake assembly having a means for locking the locking plate in a locked position to inhibit rotation of the locking plate; and an arm having a first arm end and a second arm end, the first arm end attached to the locking plate to rotate the arm about the vertically oriented central axis of the upper ring bearing, the second arm end extending at least in the horizontal direction away from the substantially vertically oriented longitudinal axis, the stopper rod depending from the second end of the arm, the method comprising the steps of simultaneously rotating the adjustment plate and rotating the arm until the stopper rod is centered in a plane over the opening in the nozzle, and locking the locking plate in the locked position when the stopper rod is centered in the plane over the opening in the nozzle.