Apparatus for heat treating steel plates

Apparatus for heat treating thin steel plate of about 3/8 inch in thickness with a minimal amount of waviness after said steel has been heated above its critical temperature comprising:

• (a) drive roller means for driving said plate through said apparatus along a path co-planar with the longitudinal axis of said plate;
• (b) means for longitudinally levelling said plate and reducing internal stresses within said plate by reversibly bending said plate in progressively smaller increments from an entrance end to an exit end of said levelling means, said levelling means including a plurality of first leveller rollers positioned on one side of said plate with centers spaced along an axis generally parallel to said path, a plurality of second leveller rollers positioned on the opposite side of said plate generally nested with respect to said first plurality and having centers spaced generally along an axis inclined relative to said longitudinal path such that the rollers in the second plurality positioned at said entrance end of said levelling means are spaced vertically closest to said first leveller rollers while the leveller rollers in the second plurality at said exit end are spaced vertically furthest from said first leveller roller, all of said leveller rollers extending transversely to said longitudinal plate axis a distance substantially equal to the width of said plate and rotatable about an axis transverse to said longitudinal axis, means for adjusting the inclined axis and simultaneously therewith the position of all of said second leveller rollers to level said plate;
• and
• (c) quench means located adjacent said exit end of said leveller means for press quenching said plate to restrain lateral and longitudinal contraction of said plate, said quench means having an entrance end and an exit end and including first and second pluralities of quench rolls positioned above and below said plate respectively with their centers on axes parallel to said longitudinal axis and extending transversely a distance substantially equal to the width of said plate and quench nozzle means interspersed between said rools for directing liquid quenchant substantially normal to said plate in a progressively controlled and uniform manner as said plate travels from said quench entrance end to said quench exit end whereby said plate is quenched with a minimal amount of flatness distortion.