As the counter dies advance towards the punches, they first come in contact with the sheet of metal to be operated upon; and after having produced the pressure which cuts out the discs, the perforations of the sheet are pushed on to the ends of the punches by the counter dies; and in order that the sheet may be allowed to advance, the carriage which supports the axles of the feeding-rollers, with the guide rod and clearing-plate, are made to slide by means of the pin m, which works in a slot in the sliding-piece n, bearing the axis of the feeding-roller l l, the slide n, being kept in its place on the frame work by dovetailed guides shown in [fig. 214.]
When the counter dies have advanced near to the sheet of metal, the pin m comes in contact with that end of the slot in the piece n, which is next to the punches, and forces the carriage with feed-rollers and clearing-plate, and also the sheet of metal, onwards, as the dies are advanced by the reaction of the cranks; and after they have cut out the discs, and raised the shanks, the sheet of metal will remain upon the punches; and when the bar e returns, the finished backs and shanks are forced out of the counter dies, by the clearing-pins and rods o o, which project through the bar e, and through the holes before mentioned in the counter dies; these clearing-pins being stationary between the bars p p, mounted upon the standard q q, on the cross bar of the frame, as shown in [figs. 210.], [212.], [213.] Immediately after this is done, the pins m come in contact with the other ends of the slots in the pieces n, and draw back the feeding-rollers l l, together with the clearing-plate k, and the sheet of metal, away from the punches into the position represented in the figures.
At this time the feeding of the metal into the machine is effected by a crank-pin r, on the end of the crank-shafts coming in contact with the bent end of the sliding-bar s, supported in standards t t; and as the crank-shaft revolves, this pin r forces the bar s forward, and causes the tooth or pall u, on its reverse end, to drive the racket-wheel v, one or more teeth; and as the racket-wheel v is fixed on to the end of the axle of one of the rollers l, it will cause that roller to revolve; and by means of the pair of spur-pinions on the other ends of the axles of the feeding-rollers, they will both revolve simultaneously, and thereby draw down the sheet of metal into the machine. It will be perceived that the standards which support the clearing-plate and guide-bar are carried by the axles of the feeding rollers, and partake of their sliding motion: also that the clearing-pins o, are made adjustable between the bars p, to correspond with the counter dies. There is an adjustable sliding stop x upon the bar s, which comes in contact with the back standard t, and prevents the bar s sliding back too far, and consequently regulates the quantity of sheet metal to be fed into the machine by the pall and ratchet-wheel, in order to suit different sizes of punches and dies. In case the weight of the bar c, carrying the counter dies, should wear upon its bearings, the guide pins g g, have small friction-rollers y y, shown under the bosses of this bar, which friction-rollers run upon adjustable beds or planes z z, by which means the guide pins may be partially relieved from the weight of the bar c, and the friction consequently diminished.
[C.]
CABLE. (Cable, Fr.; Ankertau, Germ.) A strong rope or chain, connecting the ship with the anchor for the purpose of mooring it to the ground. The sheet anchor cable is the strongest, and is used at sea; the stream cable is more slender, being used chiefly in rivers. A cable’s length is 120 fathoms. The greatest improvement in mooring vessels has been the introduction of the chain cable, which, when duly let out, affords in the weight of its long catenary curve, an elastic tension and play to the ship under the pressure of wind. The dead strain upon the anchor is thus greatly reduced, and the sudden pull by which the flukes or arms are readily snapped is in a great measure obviated. The best iron cables are chains made of links, bound and braced by rods across their middle. Experience has taught that the ends of these links wear out much sooner than the sides. To remedy this evil, Mr. Hawkes, iron manufacturer, obtained a patent in July, 1828, for constructing these anchor chains with links considerably stouter at the ends than in the middle. With this view, he forms the short rods of iron, of which the links are to be made, with swells or protuberances about one third of their length from each of their ends, so that when these are welded together, the slenderer parts are at the sides, and the thicker at the ends of the elliptic links. Such rods as the above are formed at once by rolling, swagging, or any other means. When the link is welded, it may be strengthened, by a brace or stretcher fixed across the middle.
The first avowed proposal to substitute iron cables for cordage in the sea service, was made by Mr. Slater, surgeon of the navy, who obtained a patent for the plan in 1808, though he does not seem to have had the means of carrying it into effect; a very general misfortune with ingenious projectors. It was Captain Brown of the West India merchant service who, in 1811, first employed chain cables in the vessel Penelope, of 400 tons burden, of which he was captain. He made a voyage in this ship from England to Martinique and Guadaloupe and home again, in the course of four months, having anchored many times in every variety of ground without any accident. He multiplied his trials, and acquired certain proofs that iron might be substituted for hemp in making cables, not only for mooring vessels, but for the standing rigging. Since this period chain cables have been universally introduced into all the ships of the royal navy, but the twisted links employed at first by Brown, have been replaced by straight ones, stayed in the middle with a cross rod, the contrivance of Mr. Brunton, which was secured by patent in this country and in France; but the latter patent was suffered to fall from not being acted upon within the two years specified by law.
The first thing to be considered in the manufacture of iron cables is, to procure a material of the best quality, and, in using it, always to keep in view the direction of the strain, in order to oppose the maximum strength of the iron to it. The best form of the links may be deduced from the following investigation.