Scientific American Supplement No. 819, September 12, 1891

by Various

a a are one pair of diametrically opposite webs, and a' a' the other pair of webs of the bar.

The first operation illustrated in Fig. 1 is to punch out of the edge of one of the webs, a, a series of shallow notches, b, at equal intervals apart, corresponding to the pitch of the links to be formed out of that pair of webs and situated where the spaces will ultimately be formed between the ends of that series of links. The notches are made with beveled ends, and are no deeper than is absolutely necessary (for the purpose of a guide stop in the subsequent operations, as hereinafter described), so as to avoid, as far as possible, weakening the bar transversely. This operation is repeated upon one of the pairs of webs a'; but whereas in the first operation of notching the web the "pitch" of the notches is determined by the feed mechanism, in this second operation of notching the notches, b, cut in the web, a, serve as guides to influence and compensate for any inaccuracy of the feed mechanism, so that the second set of notches, b', shall be intermediate of and rigorously equidistant from the first set of notches, b. This compensation is effected by the notches, b, fitting on to a beveled stop on the bed of the punching tool by which the notches, b', are cut, the beveled ends of the notches, b, causing the bar under the pressure of the punch to adjust itself in the longitudinal direction (if necessary) sufficiently to rectify any inaccuracy of feed. These notches, b b', similarly serve as guides to insure uniformity of spacing in the subsequent operations of punching out the links.

The second operation (illustrated in Fig. 2) is to punch out of the pair of opposite webs, a a, pairs of oblong mortises—two pairs, c c, and one pair, d d. These three pairs of mortises (which might be punched at separate operations, but are preferably punched at one stroke of the press) are situated as close as possible up to the faces of the other pairs of webs, a' a', the pairs of mortises, c c, being so spaced as to correspond in position to the eyes of the links to be formed, to which they correspond approximately in form, while the pair, d, correspond in position to the notches, b, and therefore to the intervals by which the links formed out of the same pair of webs, a a, will be separated when completed. This operation is continued along the whole length of the pair of webs, a. It will be observed that a considerable thickness of metal is left at a* between the notches, b, and the mortises, d. This is of primary importance and is one of the essential features of my method of manufacture, inasmuch as by first punching out the mortises, d, the subsequent removal of the metal from between the outer ends of the links is greatly facilitated, while by leaving the solid metal, a*, the transverse strength of the webs, a a, is not materially diminished, so that when the operation of punching the mortises, c and d, in the other pair of webs, a', is performed the bar will not be bent and crippled, as would inevitably be the case were the whole of the metal opposite the notches, b, which is ultimately to be removed, to be punched out at so early a stage of the manufacture. The operation of punching the pairs of mortises, c' and d, having been repeated along the other pair of webs, a', it will be observed that like the notches, b, the mortises, c d, in the one pair of webs alternate with those, c' d', in the other pair of webs.

The third operation (illustrated in Fig. 3) is to elongate the mortises, c d, and bring the mortises, c c', more nearly to the final form. This is performed by punches similar to but larger (in the direction of the length of the rod) than those used in the second operation.

The third operation, which is repeated upon both pairs of webs, a a a' a', may be considered as a second stage of the second operation, it being preferable to punch out the mortises in two stages in order to remove sufficient metal without unduly straining the bar.

The fourth operation (illustrated in Fig. 4) consists in roughly shaping the ends of the links externally by punching out the portions, a*, of the webs, a, between the links lying in the same plane or formed out of the same pair of webs. This operation is repeated on the other pair of webs, a'. Up to this point a continuous core of metal has been left at the intersection of the two pairs of webs.

The fifth operation (illustrated in Fig. 5) consists in punching out the portions, e, of the core at each side of the cross stay of the link, so as to separate the cross stay from the outer ends of the adjacent links. This operation is performed by removing a portion only of the metal of the core which intervenes between the cross stay and the outer ends of the adjacent links enchained with the link under operation—that is to say, portions, e*, of the core are temporarily left attached to the outer ends of the links in order to avoid crippling or bending the bar, which might occur were the whole of this metal, which is ultimately to be removed, to be punched out at once, these portions, e*, being supported by the bed die in the operation of punching out the spaces, e, as hereinafter described. This operation having been repeated upon both pairs of webs, it will be observed that the rod-like form of the chain is now only maintained by the portion of the core at the points, f, where the inner side of the eye or bow of one link is united with that of the next one. The severing of these intervening portions of the core and the breaking up of the rod into the constituent links of the chain constitute the sixth operation.

The sixth operation (illustrated in Fig. 6) is performed by torsion, and for this purpose one end of the rod is held fixed while the other is twisted once or twice in opposite directions, until by fatigue of the metal at the points, f, the whole of the links are severed almost at the same instant, and a chain of roughly formed stayed links is produced.

The seventh operation (illustrated in Fig. 7) is to remove the superfluous projecting pieces of metal both from the inside and outside of the ends of the links. For this purpose the two ends of each link are operated on at the same time by two pairs of punches corresponding to the outline of the ends of the link.

The eighth operation (illustrated in Fig. 8) is to bring the ends of the links to their finished rounded form. This is performed by stamping both ends of each link at the same time between pairs of shaping dies or swages.