Bul′let-mak′ing ma-chine.
Leaden bullets, as well for the military service as for other purposes, were formerly all made by casting.
The most common form of bullet-mold, where
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large numbers of bullets were required, was precisely like the common bullet-mold, but casting four, six, or more bullets.
The gates were afterward cut off and the bullet trimmed by hand.
The whole process was slow, and required a comparatively large number of hands.
To increase the rapidity of fabrication, revolving bullet-molds were tried, consisting of a cylindrical ring, to which revolution was imparted by a handcrank and gearing, the molten lead being fed to the mold during its revolution; the gates were cut by a knife attached to the mold at the same operation; when full, the mold was opened and the bullets discharged, after which the mold was clamped shut again and the operation recommenced.
These contrivances were ingenious, but were very liable to get out of order.
In 1857, De Zeng invented a mold for elongated bullets, constructed very similarly to the ordinary bullet-mold on a large scale, but which was mounted on a stand and worked by means of a treadle, through which, aided by the hands of the operator on the handles, the mold was opened and closed, and the gates cut off. This was an ingenious and efficient apparatus, and, with the aid of a boy to pour the lead, could be worked with great rapidity, seemingly limited only by the time required for the cooling of the metal at each cast.
Pressed leaden bullets are undoubtedly superior to cast ones, and those for the ordinary arms in the military service are made in the former way. The lead is generally procured in the form of “bullet wire,” coiled on reels.
This is cut in lengths of 25 inches, and fed to the machine by a boy. Elongated bullets are formed by a three-part die, which opens and closes with great rapidity, delivering the bullets at the rate of about 3,000 per hour; these have a slight burr or feather at the points where the dies come together, which is afterwards trimmed off by hand.
Molds and rolls are provided with each machine, so that the bars may be cast from the pig, and rolled to give them density; but, as observed above, the lead is generally procured in the form of wire.
It is estimated that a man can cast 1,500 bars, or trim and roll 2,000 bars, in a day of ten hours.
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Bruff's bullet-compressing machine. |
Bruff's machine, 1813, has a furnace and a press, in which respectively the lead is cast into ingots and made into round bullets.
The figures are side and end views of the press.
The lead is cast into flat plates of the required thickness, and of a width equal to the length of the rolls.
It passes from above, downward, between the upper pair of rolls
A, which are grooved longitudinally; by them it is pressed into round rods, — or, more correctly, long cylindrical pieces, — one half of each of which is formed by the groove in the face of one roll, while the other half is formed by the corresponding groove in the opposite roll, the two working in apposition and moving at an equal rate.
Each bar, as it falls from the upper rolls, alights upon the lower roll
B, which is grooved circumferentially, and carries the round bar against the curved steel plate
C, whose face is grooved in correspondence to the grooves of the wheel
B. The bar is nipped between the surfaces, and is cut into sections by the adjacent edges of the roll and plate, and as the pieces roll down in the grooves of the plate and are pressed on the opposite sides in the grooves of the roll, they gradually assume a perfectly spherical form and are discharged.
The elongated shot or bullets now used for rifles are made at
Woolwich in the following way: The machine for this purpose consists of four sets of duplicate punches and dies, independently worked in pairs by two eccentrics, driven by gearing from two separate driving-shafts.
The lead, coiled round four reels, is fed from them through a shearing-lever into the grippers, where it is clutched; a piece is cut to a suitable length by an upward movement of the shearing-lever; the grippers then open, the piece cut off falls down, and is clutched by another piece of apparatus.
At this moment a punch advances, and presses the lead into the die, thus forming a bullet.
A small plate comes up immediately in front of the die, and the bullet is pushed through it by a small pin, worked by a lever and cam; by this operation the ragged edge is removed which had been left on the bullet by the die. The machinery, when driven at the rate of thirty revolutions per minute, will make 120 bullets in that time, or 72,000 in a day of ten hours.
