Process of manufacturing iron cables

—The implements and operations are arranged in the following order :— 1. A reverberatory furnace (see Iron ), in which a number of rods or round bars of the best po ible wrought-iron, and of proper dimensions, are heated to bright ignition. 2. The cutting by a machine of these bars, in equal lengths, but with opposite bevels, to allow of the requisite cro ing and splicing of the ends in the act of welding. 3. The bending of each of these pieces by a machine, so as to form the links; the last two operations are done rapidly while the iron is red-hot. 4. The welding of the links at small forge fires, fitted with tools for this expre purpose, and the immediate introduction of the stay, by means of a compound lever pre . 5. Proving the strength of the cables by an hydraulic pre , worked by two men turning a winch furnished with a fly wheel. The furnace is like those used in the sheet-iron works, but somewhat larger, and needs no particular description here. IMG:4147767755307473660_illo0204-5.png:Rod shears Figs. 222. and 223. are a plan and elevation of the shears with which the rods are cut into equal pieces, for forming each a link. It is moved at Mr. Brunton’s factory by a small steam engine, but, for the sake of simplicity, it is here represented worked by four or more labourers, as it may be in any establishment. These must be relieved however frequently by others, for I believe each shears’ machine is calculated to require nearly one horse in steam power. It is portable and must be placed in the neighbourhood of both the furnace and bending machine. A and B are the two cast-iron limbs of the shears. The first is fixed and the second is movable by means of a crank shaft C , driven by a heavy fly-wheel weighing 7 or 8 cwt. The cutting jaws G are mounted with pieces of steel which are made fast by bolts, and may be changed at pleasure. E , the bar of iron to be cut. It is subjected, immediately upon being taken out of the fire, to the shears, under a determinate uniform angle, care being taken not to let it turn round upon its axis, lest the planes of the succe ive incisions should become unequal. F is a stop which serves to determine, for the same kind of chain, the equality of length in the link pieces. IMG:4147767755307473660_illo0205.png:Link bending machine Figs. 224 , 225 , 226. plan and elevations of the machine for bending the links into an elliptic form. It is represented at the moment when a link is getting bent upon it. A is an elliptic mandrel of cast-iron; it is fixed upon the top of a wooden pillar B , solidly supported in the ground. C is the jaw of the vice, pre ed by a square-headed screw against the mandrel A . D part of the mandrel comprehended between X and Y , formed as an inclined plane, so as to preserve an interval equal to the diameter of the rod between the two surfaces that are to be welded together. E rectangular slots (shears) pa ing through the centre of the nut of the mandrel, in which each of the pins F may be freely slidden. G horizontal lever of wrought-iron six feet long. It carries at H a pulley or friction-roller of steel, whose position may be altered according to the diameter of the links. It is obvious that as many mandrels are required as there are sizes and shapes of links. The piece of iron intended to form a link being cut, is carried, while red-hot, to the bending machine, where it is seized with the jaw of the vice C , by one of its ends, the slant of the cut being turned upwards; this piece of iron has now the horizontal direction m n ; on pushing the lever G in the line of the arrow, the roller H will force m n to be applied succe ively in the elliptic groove of the mandrel; thus finally the two faces that are to be welded together will be placed right opposite each other. The length of the small diameter of the ellipse ought to exceed by a little the length of the stay-piece, to allow of this being readily introduced. The difference between the points F , E is equal to the difference of the radii vectores of the ellipse. Hence it will be always easy to find the eccentricity of the ellipse. IMG:4147767755307473660_illo0206.png:Lever pre  Fig. 227. is a lever pre for squeezing the links upon their stays, after the links are welded. This machine consists of a strong cast-iron piece A , in the form of a square, of which one of the branches is laid horizontally, and fixed to a solid bed by means of bolts; the other branch, composed of two cheeks, leaving between them a space of two inches, stands upright. These two cheeks are united at top, and on the back of their plane by a cro piece B . C , a rectangular staple, placed to the right and left of the cheeks through which is pa ed the mandrel D , which represents and keeps the place of the following link. E , is a pre lever, 6 feet long. F , clamp and counter clamp, between which the link is pre ed at the moment when the stay is properly placed. There are other clamps, as well as staples C , for changing with each changed dimension of links. The links bent, as we have seen, are carried to the forge hearth to be welded, and to receive their stay; two operations performed at one heating. Whenever the welding is finished, while the iron is still red-hot, the link is placed upright between the clamps F ; then a workman introduces into the staple the mandrel D , and now applies the stay with a pair of tongs or pincers, while another workman strikes down the lever E forcibly upon it. This mechanical compre ion first of all joins perfectly the sides of the link against the concave ends of the stay, and afterwards the retraction of the iron on cooling increases still more this compre ion. If each link be made with the same care, the cable must be sound throughout. It is not delivered for use however till it be proved by the hydraulic pre , at a draw-bench made on purpose. The pre is an horizontal one, having the axis of its ram in the middle line of the draw-bench, which is about 60 feet long, and is secured to the body of the pre by strong bolts. The portion of chain under trial, being attached at the one end to the end of the ram of the pre , and at the other to a cro -bar at the extremity of the draw-bench, two men put the pre in action, by turning the winch which works by a triple crank three forcing pumps alternately; the action being equalized by means of a heavy fly-wheel. As long as the resistance does not exceed the force of two men, the whole three pumps are kept in play. After a while one pump is thrown out of geer and next another, only one being worked towards the conclusion. The velocity of the ram being retarded first one third and next two thirds, gives the men a proportional increase of mechanical power. The strength of two average men thus applied being computed, enables us to know at every instant the resistance opposed by the chain to the pre ure of the ram. The strain usually applied to the stronger cables is about 500 tons. The side beams of the draw-bench are of cast-iron, 6 inches in diameter; the different pieces composing it are adjusted to each other end-wise by turned joints. Props also of cast-iron support the beams two feet asunder, and at the height of 30 inches above the ground. The space between them is filled with an oak plank on which the trial chain is laid. Strength of iron-cables compared to hemp cables :— | Iron Cables. Diameter of Iron Rod. | Hemp Cables. Circumference of Rope. | Resistance. | | Inches. | Inches. | Tons. | | 0 | 7⁄8 | 9 | | 12 | | 1 | | 10 | | 18 | | 1 | 1⁄8 | 11 | | 26 | | 1 | 1⁄4 | 12 | | 32 | | 1 | 5⁄16 | 13 | | 35 | | 1 | 3⁄8 | 14 | to 15 | 38 | | 1 | 1⁄2 | 16 | | 44 | | 1 | 5⁄8 | 17 | | 52 | | 1 | 3⁄4 | 18 | | 60 | | 1 | 7⁄8 | 20 | | 70 | | 2 | | 22 | to 24 | 80 | It would be imprudent to put hemp cables to severer strains than those indicated in the preceding table, drawn up from Brunton’s experiments; but the iron cables of the above sizes will support a double strain without breaking. They ought never in common cases however to be exposed to a greater stre . A cable destined for ships of a certain tonnage, should not be employed in those of greater burden. Thus treated it may be always trusted to do its duty, and will last longer than the ship to which it belongs. A considerable part of this decided superiority which iron cables have over hemp ones, is undoubtedly due to the admirable form contrived by Brunton. Repeated experiments have proved that his cables po e double the strength of the iron rods with which they are made—a fact which demonstrates that no stronger form can be devised or is in fact po ible. One of the most valuable qualities of iron cables is their resisting lateral as well as longitudinal strains as explained under figs. 219. and 221. Ve els furnished with such cables have been saved by them from the most imminent peril. The Henry, sent out with army stores during the peninsular war, was caught on the northern coast of Spain in a furious storm. She run for shelter into the Bay of Biscay among the rocks, where she was exposed for three days to the hurricane. She po e ed fortunately one of Brunton’s 70 fathom chain cables, which held good all the time, but it was found afterwards to have had the links of its lower portion polished bright by attrition against the rocky bottom. A hemp cable would have been speedily torn to pieces in such a predicament. In the contracts of the Admiralty for chain cables for the British navy, it is stipulated that “the iron shall have been manufactured in the best manner from pig iron, smelted from iron-stone only, and selected of the best quality for the purpose, and shall not have received in any proce whatever subsequent to the smelting, the admixture of either the cinder or oxides produced in the manufacture of iron; and shall also have been puddled in the best manner upon iron bottoms, and at least three times sufficiently drawn out at three distinct welding heats, and at least twice properly fagotted.” The following is a table of the breaking proof of chain cables, and of the iron for the purpose of making them, also of the proofs required by her majesty’s navy for chains. | Size of Bolt. | Proof of Bolt. | Proof of Chain. | Navy Proof of Chain. | | Inches. | Tons. | Cwt. | Tons. | Cwt. | Tons. | | 1⁄2 | 5 | 7 | 8 | 11 | 4 | 1⁄2 | | 5⁄8 | 8 | 7 | 13 | 4 | 5 | 1⁄2 | | 3⁄4 | 12 | 1 | 19 | 5 | 10 | 7⁄8 | | 7⁄8 | 16 | 4 | 26 | 5 | 13 | 3⁄4 | | 1 | | 21 | 8 | 34 | 5 | 18 | | | 1 | 1⁄8 | 27 | 2 | 48 | 15 | 22 | 3⁄4 | | 1 | 1⁄4 | 33 | 10 | 53 | 11 | 28 | 1⁄2 | | 1 | 3⁄8 | 40 | 10 | 65 | 0 | 34 | | | 1 | 1⁄2 | 48 | 4 | 77 | 0 | 40 | 1⁄2 | | 1 | 5⁄8 | 56 | 11 | 90 | 10 | 47 | 1⁄2 | | 1 | 3⁄4 | 65 | 12 | 105 | 0 | 55 | 1⁄8 | | 1 | 7⁄8 | 75 | 6 | 120 | 10 | 63 | 1⁄4 | | 2 | | 85 | 14 | 137 | 0 | 72 | | | 2 | 1⁄8 | 96 | 15 | 155 | 0 | 81 | 1⁄4 | In Brunton’s cable the matter in the link is thrown very much into one plane; the link being of an oval form, and provided with a stay. As there are emergencies in which the cable must be severed, this is accomplished in those of iron by means of a bolt and sheckle (shackle), at every fathom or two fathoms; so that by striking out this bolt or pin, this cable is parted with more ease than a hempen one can be cut.