(57) A billet heating furnace of the enclosed skid type comprises a feed mechanism (47)
for regularly adding to and pushing a row of billets along a skid (31) extending through
a furnace chamber (22) which is formed by a lower section (1) and an upper section
(2) hinged to the lower section so that the chamber can be opened and closed. The
furnace is heated by at least one high velocity premix gas burner (28) mounted in
the upper section of the furnace chamber and controlled so as to raise and maintain
an operating temperature in the chamber which is higher than the melting temperature
of the billets and which is effective to raise the temperature of the billets passing
through the furnace chamber to a suitable stamping temperature. At the outlet end
of the furnace chamber the heated billets move onto a delivery path (55, 56, 57) for
passage to a press. Along this path there is a billet detector (58 to 63) which responds
to any interruption of the regular passage of billets to shut down the burners. The
furnace chamber (22) is lined with ceramic fibre material (21) having a low thermal
mass such that, if the burners (28) are shut down and there are billets stationary
in the furnace chamber, the temperature in the chamber will fall I to below the melting temperature of the billets before the temperature of the billets
can rise to the melting tempera- , ture. At the same time as the burners are shut
down, a slide (64) in the delivery path (65) is opened so that any billets subsequently
leaving the furnace chamber will be directed down a reject chute (66) until the furnace
operator decides that the feed to the press is ready to be recommenced.
|
|
