Improving the Lining of Cars Used in Short Tunnel Furnaces

An improved design of lining has been developed for the cars of short PG-30 tunnel furnaces, which are used to fire ceramic tooling: crucibles, cores, and molds for casting products made of heat-resistant alloys. The top part of the refractory layer that is installed on the heat-insulating layer consists of two superimposed panels. All of the panels except for the top panel contain interrupted holes (a total of 44 such holes) that are arranged in staggered fashion and open onto the panels' main surfaces. The top panel contains blind holes (totalling 22). In assembling the refractory layer, the ends of the panels are connected to one another in such a way that the holes their surfaces are coaxial. The top panel is positioned so that the surface without holes faces upward and the holes on the other surface face downward. The box-inserts that hold the ceramic products which are to be fired are placed on the top panel. Such a design of car significantly reduces its weight while also increasing its service life. Durability is improved in particular for high-speed operation of the cars, such as in the firing of foundry molds for casting nickel alloys.