As with intermediate heating, vertical coils are usually used for post-heating, in which the billets are heated to the target temperature.
It is used for the precise heating of the billets for the extrusion press.
During the hole punching process, the block cools unevenly. However, since the extrusion press requires suitably tempered, evenly heated billets, post-heating has to fulfil two important tasks. On the one hand, the billet must be heated to a final temperature of approx. 1250 °C and, on the other hand, the temperature must be evenly distributed over the billet.
For this purpose, vertical single-billet multi-zone induction furnaces are used for post-heating. The induction coils of these furnaces are divided into several zones, each of which is equipped with a non-contact temperature measuring station.
Depending on the measured surface temperatures, the energy input is dimensioned in zones, which leads to a homogeneous temperature distribution over the entire billet.
The billet to be heated is removed from the roller conveyor system and brought into a vertical position by means of a swivelling device. An electrically powered lifting mechanism positions the billets into the induction coils.
Once the target temperature has been reached and the billet has been requested by the extrusion press, it is lowered and conveyed to the press via the roller conveyor system.