"A.G. Davis - AA Gage Stack Gage Solves High-Accuracy, Heavy Load Capacity Assembly/Allignment Challenge

To assist a major manufacturer of stationary gas turbines with multi-stage rotor shaft assembly and alignment, A. G. Davis - AA Gage designed and built a stack gage that meets the requirements of high accuracy and heavy load capacity.

Heart of the stack gage is a 48" servo-controlled, air-bearing rotary table propelled by an anti-backlash capstan drive system. The air float system allows loads of up to 50,000 Ibs. to be positioned accurately with minimum friction. Table design includes an X-Y adjustment for setting concentricity and a three-point wobble adjustment. Also included is a pivoting leaf probe holder containing twelve L.V.D.T.'s.

The table and adjustments are controlled by a two-axis computer servo system. One axis drives the table and has an encoder for feedback; and the other drives the X-Y and wobble adjustments. The system has a radial runout of .0002 inches at a distance of 10' feet above the table.

Assembly/alignment begins with the first stage being mounted to the rotary table which contains a rough locator, The probe holder leaf is then assembled into position and staked. The control automatically rotates the table while reading the L,V.D.T,'s and the servo adjustment positioner makes X-Y and wobble adjustments to the best fit plane. The probe holder riser is then added so that the second stage can be aligned and mounted to the first stage. The process continues until all stages are assembled.