[Fig. 3046] represents a Bradley’s Cushioned Hammer, in which motion is obtained by a belt passing over a pulley on a crank shaft, whose connecting rod r is capable of adjustment for length, so as to govern the distance to which the hammer shall fall, which obviously varies with different sizes of work. The hammer is lifted through the medium of a rubber cushion a, seated in a casting to one end of which is connected the rod r, while the other end is pivoted. The lever to which the hammer is affixed is raised against the compression of the rubber cushion b, and at the top of its stroke also meets the rubber cushion c; hence these two cushions accelerate its motion after the crank has passed its highest point of revolution. The cushion d prevents the rebound of the hammer after the blow is struck; hence as a result of these cushions, heavy or light blows may be struck with great rapidity and regularity. The weight w is on a lever that actuates a break upon the wheel shown at the side, so as to enable the stopping of the hammer quickly. The machine is put in motion by pressing the foot upon the treadle t, which operates a belt tightener, the belt running loose when the treadle is released.
The hammer lever or helve is adjustable for height by means of the screw g and hand-wheel h, which raise or lower the bearings in which the helve journals are carried. This is necessary, because as the helve moves in the arc of a circle the faces of the upper and lower die, or of the hammer and the anvil, as the case may be, can only come fair at one particular point in the path of the hammer; hence in proportion as the blow terminates (by meeting the work surface) farther from the anvil face, the pivot or journal of the helve must be raised, so that the journal will be horizontally level (or as nearly so as possible) with the hammer face at the moment the blow is delivered.
By giving motion to the helve through the medium of cushions, a direct mechanical connection, and the destructive concussion that would accompany the same, is avoided; hence a high speed may be obtained without the frequent breakage that would otherwise ensue.
Fig. 3047.
[Fig. 3047] represents Corr’s power hammer, the construction being as follows: The semi-elliptic springs, shown on top and bottom of the beam, serve to balance the stroke, so that the hammer may run from 350 to 450 strokes per minute, with safety to the machinery. The hammer is adapted to almost any form or kind of forging. Large dies may be inserted for various kinds of forming and welding, such as making plough-shares and other articles, which require that the operation be commenced with a light tap, and increased to a heavy blow at the will of the operator.
The whole structure is mounted on a substantial iron bed v, 18 inches deep, 22 inches wide and 51⁄2 feet long. Attached to this bed v are two circular arms l; between them is pivoted near their top, at k, an oscillating frame h, having a longitudinal opening, in which is attached two semi-elliptic springs g g, and two plates i, with trunnions projecting laterally through the oscillating frame at k; the hammer beam f is inserted between the springs g g, and the trunnion plates i, which are bolted firmly to beam f at i; the ends of the trunnions and outsides of the oscillating frame h rest evenly against the inside of the circular arms l; at k a shaft is passed through the trunnions and beam f, and made rigid in them with its ends resting in boxing at k. Caps are provided to cover the ends of the boxing and shaft with set-screws projecting against the ends of the shaft, which secures it against end play.
By these mechanical arrangements the beam f and oscillator h are securely attached independently, vibrating on one common centre, allowing no side play of the hammer e, admitting f to the free action of the springs g g; in the lower end of the oscillating frame at n is a lateral opening 10 inches vertically by 6 inches longitudinally and 4 inches laterally, with flanges projecting longitudinally one inch into this opening from both sides. This makes the opening two inches smaller on the outside than the internal cavity; the rear and front internal walls are provided with steel plates, 4 by 10 inches, 1⁄4 thick, resting against the inner ends of four set-screws, not shown, provided to adjust these plates to or from the sliding box at n, to compensate for wear and prevent lost motion. These plates and flanges form slides and guides between which a loose box and eccentric is provided with shaft projecting laterally through boxing at n, which project upwards from an adjustable frame immediately under the oscillator h; this permanently locates the eccentric and shaft in the lateral opening in the oscillator h, at n. The adjustable frame mentioned rests on suitable bearings on the inside of the circular arms l, and is fastened down by four bolts passing through suitable slots in the adjustable frame, entering the bearings on the arms l. This frame is adjusted back or forth by set-screws s s; this adjustment is for the purpose of giving a greater or less distance between the anvil and hammer at d, as may be desired for large or small work, long or short dies, &c.
The anvil b, weighing about 500 lbs., sits down in the bed at r and rests on circular bearings (between r and b), which radiate to the centre of the top of the anvil at d, and is held rigidly in any position longitudinally desired by set-screws q q, with their inner ends resting on shoulders on the sides of the anvil b, which projects down about ten inches; between this lower projection and the internal wall of the bed is sufficient space to admit of any adjustment desired. This lateral adjustment is accomplished by set-screws r, passing through the sides of the bed v, with their inner ends resting against the anvil which holds it rigid at any lateral adjustment. By this arrangement the anvil is accommodated to all and any class of work or shape of dies.