Low profile turntable assembly
A large rectangular rotary table includes a fabricated tubular metal frame having top plates for supporting fixtures and large motor vehicle parts. A center portion of the table frame is supported by an annular turret bearing mounted on a base plate spaced above a floor plate by adjustable leveling screws. A drive unit is also supported by the base plate within the bearing and the center portion of the table frame and includes a planocentric gear reducer driven by an electric servo motor projecting above the table. A laterally projecting torque arm is mounted on the output of the gear reducer and is connected to the table frame by a sliding drive pin assembly which prevents radial loads on the gear reducer when the table is indexed. A fluid actuated table locating pin alternately engages a locating seat on each end of the table after the table is indexed.
1. A low profile turntable assembly in combination with a horizontal supporting floor for transferring large parts having substantial weight between work stations, said assembly comprising
a fabricated metal table frame positioned adjacent said floor and including horizontally extending and parallel spaced crossing frame members,
an annular center support plate mounted on said frame members and defining a central opening for said table frame,
said table including horizontally spaced support members positioned horizontally outwardly from said center support plate for supporting the parts,
a horizontal stationary base plate positioned within said frame and secured to a floor plate mounted on said floor,
an annular turret bearing mounted on said base plate within said table frame between said frame members and under said center support plate and supporting said table frame for rotation around said turret bearing adjacent said floor on a vertical axis extending through said central opening of said table frame,
a drive unit mounted on said base plate and projecting upwardly through said central opening within said center support plate and substantially above said table frame,
said drive unit including a speed reducer driven by a motor positioned above said speed reducer,
said speed reducer having a rotary output positioned within said central opening and connected to a horizontal torque member projecting radially outwardly from said speed reducer adjacent said center support plate,
a drive coupling spaced horizontally from said speed reducer and connecting said torque member to said center support plate to produce rotation of said table frame on said axis in response to actuation of said motor, and
said drive coupling providing for radial outward and radial inward movement of said table frame relative to said base plate and said speed reducer when said table frame is rotated by said drive unit to avoid horizontal loading on said drive unit by said table frame during rotation of said table frame.
2. A turntable assembly as defined in claim 1 wherein said drive coupling includes a drive shoe mounted on a drive pin connected to said torque member, and
horizontally spaced drive plates connected to said center support plate and having parallel spaced radially extending surfaces receiving said drive shoe therebetween to provide for said radial movement of said table frame relative to said base plate and said speed reducer.
3. A turntable assembly as defined in claim 1 wherein said speed reducer comprises a planocentric robotic gear reducer, and said motor comprises an electric servo motor projecting upwardly from said gear reducer in laterally offset relation to said vertical axis of said rotation of said table frame.
4. A turntable assembly as defined in claim 1 and including a plurality of adjustable jack screws threaded vertically into said base plate and engaging said floor plate to provide for precisely leveling base plate and said table frame, and a plurality of weld blocks welded to said base plate and to said floor plate after said base plate and said table frame are leveled.