This section is from "Scientific American Supplement Volumes 275, 286, 288, 299, 303, 312, 315, 324, 344 and 358". Also available from Amazon: Scientific American Reference Book.
Ever since the improvements that have been introduced into the manufacture of steel, and especially into the erection of works for its production, have made it possible to obtain this metal in very large masses, it has necessarily been preferred to iron for all pieces of large dimensions, inasmuch as it possesses in the highest degree that homogeneousness and resistance which are so difficult to obtain in the latter metal. It has consequently been found necessary to construct engines sufficiently powerful to effect the forging of enormous ingots, as well as special furnaces for heating them and apparatus for manipulating and transporting them.
The greatest efforts in this direction have been made with a view to supplying the wants of heavy artillery and of naval constructions; and to these efforts is metallurgy indebted for the creation of establishments on a scale that no one would have dared a few years ago to think of. The forging mill which we are about to describe is one of those creations which is destined to remain for a long time yet very rare; and one which is fully able to respond, not only to all present exigencies, but also, as far as can be foreseen, to all those that may arise for a long period to come. The mill is constructed as a portion of the vast works that the Compagnie des Forges et Aciéries de la Marine own at Saint Chamond, and which embrace likewise a powerful steel works that furnishes, especially, large ingots exceeding 100 tons in weight.
The mill consists, altogether, of three hammers, located in the same room, and being of unequal powers in order to respond to different requirements. The largest of these hammers is of 80 tons weight, and the other two weigh respectively 35 and 28 tons. Each of them has a corresponding furnace for heating by gas, as well as cranes for maneuvering the ingots and the different engines. The general plan view in Fig. 4 shows the arrangement of the hammers, cranes, and furnaces in the millhouse.
FIG. A.--ELEVATION OF A HAMMER. FIG. B.--PROFILE VIEW
The gas generators which supply the gas-furnaces are located out of doors, as are the steam-generators. The ingots are brought from the steel factory, and the forged pieces are taken away, by special trucks running on a system of rails. We shall now give the most important details in regard to the different parts of the works.
The Mill-House--This consists of a central room, 262 feet long, 98 feet wide, and 68 feet in height, with two lean-to annexes of 16 feet each, making the total width 100 feet. The structure is wholly of metal, and is so arranged as to permit of advantage being taken of every foot of space under cover. For this purpose the system of construction without tie-beams, known as the "De Dion type," has been adopted. Fig. 1 gives a general view of one of the trusses, and Fig. 5 shows some further details. The binding-rafters consist of four angle-irons connected by cross-bars of flat iron. The covering of corrugated galvanized iron rests directly upon the binding-rafters, the upper parts of which are covered with wood for the attachment of the corrugated metal. The spacing of these rafters is calculated according to the length of the sheets of corrugated iron, thus dispensing with the use of ordinary rafters, and making a roof which is at once very light and very durable, and consequently very economical. Rain falling on the roof flows into leaden gutters, from whence it is carried by leaders into a subterranean drain. The vertical walls of the structure are likewise of corrugated iron, and the general aspect of the building is very original and very satisfactory.
The 80 Ton Hammer--The three hammers, notwithstanding their difference in power, present similar arrangements, and scarcely vary except in dimensions. We shall confine ourselves here to a description of the 80 ton apparatus. This consists, in addition to the hammer, properly so called, of three cranes of 120 tons each, serving to maneuver the pieces to be forged, and of a fourth of 75 tons for maneuvering the working implements. These four cranes are arranged symmetrically around the hammer, and are supported at their upper extremity by metallic stays. Besides the foregoing there are three gas furnaces for heating the ingots. Figs. 1, 2, and 3 show the general arrangement of the apparatus.
Foundations of the Hammer and Composition of the Anvil-Bed--To obtain a foundation for the hammer an excavation was made to a depth of 26 feet until a bed of solid rock was reached, and upon this there was then spread a thick layer of beton, and upon this again there was placed a bed of dressed stones in the part that was to receive the anvil-stock and hammer.
On this base of dressed stones there was placed a bed formed of logs of heartwood of oak squaring 16 inches by 3 feet in height, standing upright, joined together very perfectly, and kept in close juxtaposition by a double band of iron straps joined by bolts. The object of this wooden bed was to deaden, in a great measure, the effect of the shock transmitted by the anvil-stock.
NEW EIGHTY-TON STEAM HAMMER AT THE ST CHAMOND WORKS.
FIG. 1.--TRANSVERSE SECTION.
FIG. 3.--PROFILE VIEW.
FIG. 4.--GENERAL PLAN OF THE FORGING MILL.
FIG. 5.--DETAILS OF THE TRUSSAND SUPPORT FOR THE CRANE.