Conveying sheets at non-uniform speed

Apparatus for moving a succession of discrete glass sheets into proper orientation and alignment relative to a path and maintaining said orientation and alignment while moving said glass sheets at a non-uniform speed along said path during heat treatment thereof comprising a conveyor including a first series of longitudinally spaced conveyor rolls, a second series of longitudinally spaced conveyor rolls spaced from said first series, a selected series of conveyor rolls comprising a plurality of subseries of said selected series bridging the gap between said first series and said second series, means for rotating said first series of rolls at a first speed, means for rotating said second series of rolls at a second speed faster than said first speed, a plurality of clutch means, each coupled to a different subseries of said selected series of said conveyor rolls to rotate said selected series of conveyor rolls at said second speed when engaged with its associated subseries and permitting said associated subseries of said conveyor rolls to rotate at said first speed when disengaged from said associate subseries, timing means for selectively actuating each of said plurality of clutch means in unison when one of said glass sheets is completely over said selected series and for deactivating each of said plurality of clutch means according to a predetermined time cycle, said path comprising a tunnel-type furnace comprising an alignment and orienting station located near the exit of said furnace, said station comprising means for orienting and aligning each glass sheet in succession as it is conveyed through said station in said furnace at said first speed, when orienting and aligning means comprising retractable glass edge engaging means, carriage means supporting said retractable glass edge engaging means for movement relative thereto, means for moving said carriage means downstream at said first speed while moving said glass edge engaging means into engagement with said glass sheet and then retracting said glass edge engaging means before said timing means actuates said clutch means simultaneously, means for returning said carriage means upstream with said glass edge engaging means retracted in time for the next succeeding glass sheet in said series to arrive at said station, and glass detector means responsive to the presence of each glass sheet in said series at a predetermined position to actuate said timing means, whereby said carriage means moves downstream in alignment with each said glass sheet at said first speed, said plurality of clutch means engage said associated subseries simultaneously when each glass sheet occupies a preselected position where it is completely over said selected series of said conveyor rolls, and each of said clutch means is individually disengaged from its associated subseries when the trailing edge of each glass sheet passes beyond said associated subseries.