They are then stamped out
so as to round them up, and the metal inside them is punched out, and
the edges "cleaned," or trimmed off. The links are now parted from one
another and stamped again, to insure equal thickness in all parts of
the chain. The only processes now to be gone through are dressing and
finishing. According to the die used, the shape of the links can be
varied to suit any required pattern. The lengths of chain thus made
are joined by spiral rings made of soft steel, the convolutions being
afterward hammered together till they become solid. A ring of this
description, 3/4 inch diameter, underwent a strain of 46,200 lb., that
is, 23 tons to the square inch, its elongation being 21 per cent.
These chains have passed satisfactorily the tests of the Bureau
Veritas, and both that association and Lloyd's have accepted their use
on the same conditions and under the same tests as ordinary chains.
So much for the general idea of punching steel chains. We will now
describe a recent invention by which superior steel chains are
produced, the author of which is Mr. Hippolyte Rongier, of Birmingham,
Eng. He says:
My invention has for its object the manufacture of weldless stayed
chains, whereof each link, together with its cross strut or stay, is
made of one piece of metal without any weld or joint; and the
invention consists in producing a chain of stayed links from a bar of
cruciform section by the consecutive series of punching, twisting and
stamping operations hereinafter described, the punching operations
being entirely performed on the metal when in the cold state.
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