| 摘要 |
<p>A convection heat treating oven (10), especially for reflow soldering of printed circuit boards (25), comprises a plenum (9) with entrance (13) and exit (14) ports, a conveyor (11) for conveying items through the plenum and a series of panel heaters (12) separated by gas recycle ducts within the plenum. Each panel heater directs incoming gas past a heating element (22, 122) and thence through a chamber and grid (23, 123) onto the items on the conveyor at a controlled gas velocity. Each gas recycle duct (18) intakes gas issuing from one panel heater and passes it into the adjacent panel heater. Gas from the plenum issuing from the last of the panel heaters in the series is exhausted. A matching set of panel heaters and gas recycle ducts beneath the conveyor direct heated gas upwardly toward the conveyor. The serpentine flow of gas through the oven can be concurrent or counter-current to the conveyor.</p> |
