Blakney Cupola
The Blakney cupola consists principally of a system of tuyeres, by which, it is claimed, the air is so distributed or projected into the furnace as to produce a uniform heat, giving the iron a uniform strength for all kinds of castings. The features peculiar to the above furnace are as follows:
The introduction of a combination of curved tuyeres or chutes placed upon the wall or lining of the cupola, and forming a part of the wall, a proper distance from the bottom and nearly surrounding the inner and outer sides of the wall. The tuyeres are made of cast iron and in sections for convenience of handling. A blank space is left in the rear of the cupola two feet wide, through which the slag is blown, if required.
A chamber or base extending around the cupola incloses the space in which the air is conducted to the tuyeres. The bottom of this chamber, made irregular in form, hollows at suitable intervals to allow the metal to flow to the escape openings, in case it overflows through the tuyeres. The openings are closed with fusible plugs of lead or other material to be melted out by the molten metal.
The blast is conducted to this cupola through one pipe, and, striking the blank space sidewise in rear of chamber, passes all around through the curved tuyeres into the centre of the furnace, the blast striking into the cupola every 7/8 of an inch horizontal, and 3 3/4 inches perpendicular, or according to diameter of cupola.
As a producer of a uniform grade of iron for the purpose of casting car-wheels it is just what is needed for the different grades of iron to prevent chill-cracking.
This cupola, with its many superior advantages, has also rows of shelves bolted to the shell four feet apart up to the top of the charging-door, so that it will not be necessary to tear out any of the lining except that which is burned out.
Blast is air forced into a cupola or furnace by a blowing-engine, blower, or fan for the purpose of increasing combustion. If heated it is then called hot blast, and cold blast when it enters the cupola or furnace direct from the atmosphere. See CUPOLA; BLOWERS; BLAST-PIPES.