The cover this week gives a striking picture of a forging being shaped in a hydraulic press, a method which has largely displaced the steam hammer for heavy work. This press can exert a pressure of 15,000 tons. The photograph was taken in a modern steelworks at Dortmund, South Germany.
Steel - From Ore to Ingot (photogravure supplement)
Photogravure Supplement - 1
MOLTEN IRON for conversion into various classes of steel is tapped from the cupolas (or small blast furnaces) in which pig iron is melted. This photograph was taken in a steelworks at Letchworth, Hertfordshire. Steel castings are made here and more than 1,500 men are employed.
Photogravure Supplement - 2
OPEN HEARTH FURNACES for the manufacture of steel, invented by Dr C William Siemens and improved by the brothers Martin, came into use in 1863. The open hearth furnace is a large closed chamber with a shallow saucer-shaped bed for the metal. At either end are ports for the admission of hot air and gases which form the fuel and burn over the surface of the metal. Furnaces of this type have a capacity of as much as 300 tons. The molten steel is poured from the furnaces into huge ladles handled by overhead cranes, as shown.
Photogravure Supplement - 3
THE BESSEMER CONVERTER is a large steel flask pivoted at the centre so that its mouth can be directed upwards or to the front. Molten iron is poured in and a blast or cold air causes the iron to become hotter by causing combustion in the presence of oxygen. First, the silicon burns and causes a red flame and brown smoke. When the carbon burns, a long jet of bright flame issues from the mouth of the converter. When the carbon is completely burnt, the flame disappears with remarkable suddenness. When the “blow” is finished, the converter is pivoted to the front and the metal is poured as shown in the colour plate facing page 172.
