steam hammer (stemham"er)

A forging-hammer operated by steam-power. It has a umed several forms, but now consists of a vertical and inverted steam-cylinder with piston and piston-rod (the rod pa ing through the lower cylinder-head and carrying at the end a ma of metal which forms the hammer), an anvil directly beneath the hammer and cylinder, a supporting framework, and suitable valves for the control of the steam. Steam is used to raise and may also be used to drive down the hammer. By means of the valve-system, steam is admitted below the piston to raise the hammer and to sustain it while the metal to be forged is placed on the anvil. To deliver a blow, the steam is exhausted below the piston, and the hammer is allowed to fall by its own weight. To augment the blow, live steam may be admitted above the piston to a ist in driving it downward. To deliver a gentle blow, the exhaust-steam below the piston may be retained to act as a cushion. Blows can be delivered at any point of the stroke, quickly or slowly, lightly or with the full power of the combined weight of the hammer and force of steam-pre ure; or the machine may be used as a vise or squeezer. All modern steam-hammers of the type described are modifications of the original Nasmyth steam-hammer illustrated in the cut. Steam IMG:content-2057.png:[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small] a, anvil; b, frame; c, hammer-head; d, guides; e, piston-rod; 1, valve-chests containing valves that control induction of steam to and eduction from the cylind from the cylinder h; h ', steam-pipe; g, rock-lever (moved by the rod) connected with the valve-stems and moving the valves; tripping-mechanism by which the hammer is to from any part of the upstroke, the adjusting-gear & being manipulated by a workman standing on the platform 2. hammers of the largest cla have been made with hammers weighing eighty tons. Another type of steam-hammer consists of two horizontal steam-cylinders placed in line, the hammers meeting over an anvil on which the forging rests.