Fig. 3056.
Figures from [3052] to [3056] represent a steam hammer. The head a is set at an angle in the frame. The anvil or die c is oblong, as is also the anvil die d. The object of this arrangement is to enable the workman, after drawing out his work across the short way of the die, to turn it and finish it lengthwise without being inconvenienced by the frame. By this means skew and T-shaped dies can be dispensed with, and the full service of the ram utilised. The latter is moved between the guides e e, and held in place by the steel plate f, bolted through the frame b. The valve g is a plain cylinder of cast iron, enlarged at each end to work in the cylindrical seats h h, in which the ports i i are placed. Steam is admitted through the valve j, and circulates round the valve g, between the seats. The exhaust chamber k is below the cylinder, which therefore drains condensed steam into it at each stroke through the lower steam port. The exhaust above the piston passes down through the interior of the valve, as shown by the arrow on the drawing. The valve stem l is connected with the valves in the exhaust chamber. No stuffing box is therefore required, there being only atmospheric pressure on each side of it. This combination enables the valve to be so perfectly balanced that it will drop by its own weight while under steam.
The automatic motion is obtained by an inclined plane m upon the ram a, which actuates the rocker n, the outer arm of which is connected by a link to the valve stem, and thus gives motion to the valve. The valve is caused to rise in the up-stroke by means of the rocker n and its connections, through the inclined plane. The steam is thus admitted to the top, which drives down the piston, while the valve and its connections follow by gravity, thus reducing considerably the friction and wear upon the valves. In very quick work the fall of the valves may be accelerated by the aid of a spring; or it may be retarded in heavy work by friction springs, so as to obtain a heavier blow by a fuller admission of steam. For general work, however, the arrangement shown is perfectly effective, and as the rocker n is hung upon the adjustment lever p, any required variation can be obtained by the movement of the lever. Single blows can be struck with any degree of force, or a rapid succession of constant or variable strokes may be given.
The anvil o rests upon a separate foundation, in order to reduce the effect of concussion upon the frame. The drawing illustrates the arrangement. The bed is long, extending beyond the hammer on each side so as to give plenty of area, and the ends are left open for convenient access in case the anvil should settle and require re-adjustment.
Other forms of hammers having the same general principles of construction are as follows:—
Fig. 3057.
[Fig. 3057] represents a double frame hammer, the weight of the hammer being supplemented by steam pressure. The spiral springs shown beneath the cylinder are to prevent the hammer from striking the cylinder and causing breakage from careless handling by the operator. The valve gear is arranged for operation either automatically or by hand.