Nail Manufacture - wire, nails, type, feed, cut, head, forward and table

NAIL MANUFACTURE. Iron nails were commonly in use during the Roman occupation of Britain, large numbers having been found in places where they were wrought by the Romans. There is a striking similarity between the forged Roman nail (fig.') and the type of nail which is manufactured at the present time. The forging of nails was an industry of some importance in Great Britain up to the end of the 17th century, and only gave way before the advent of machinery and the cut and machine headed nail. During the year 1927, 20,000 tons of wire nails were manufactured in Great Britain, whilst another 6o,000 tons were imported.

Wire Nails.—The use of wire for nail making has completely revolutionized the method of manufacture; nails made from drawn wire are produced so cheaply that they can be purchased at almost the same price as the wire from which they are made. Cut nails, sheared from plates or flat stock, are produced, but the quan tities in which these nails are used are so small, compared to the production of round wire nails, that cut nails are now negligible items.

Catalogues of prominent nail manufacturers show nearly roo different types of nails or fasteners made of round wire, but the number of items, by gauges and sizes, run over 400. Figure shows many common types of wire nails, (a) common nail, (b) barbed car nail, (c) finishing nail, (d) clinch nail, (e) slating nail, (f) countersunk head, (g) double-head form nail, (h) flooring brad, (i) broom nail, (j) roofing nail, (k) fine nail.

Screw type (in) nails have been developed and are used to some extent, principally as roofing nails. This type of nail tends to drive more easily, rotates as it enters the wood and retains greater holding power than does a similar nail of round wire. One method in common use for the manufacture of this type of nail is to pro duce it as a round wire nail and then pass the nail between two rolls and roll into the shank four or five spiral flutes. Another type of nail, developed to increase holding power, has annular serrations or saw-tooth ridges around the shank that are designed to bite into the grain of the wood when forces tend to withdraw the nail. This particular type of nail is used to some extent for fastening composition type shingles and siding.

Forming wire nails is a typical cold heading operation. Stresses and pressures in various parts of the nail machine are great and nail machines are relatively massive. There are principally four component parts in a nail machine; a hammer mounted in a cross head to which is imparted reciprocating motion through a connect ing-rod and a crankshaft, a set of cam-actuated slides which hold case-hardened tools that form the point and cut the nail after it is headed, another set of cam-actuated slides which hold the dies that grip the round wire and act as an anvil for the hammer form ing the head, and a reciprocating feed table which straightens the wire as it unwinds from the coil and feeds through the heading dies the proper amount of wire stock for the nail. In operation,

the feed table straightens and forces wire through the header dies in sufficient amount to provide stock for the head. the header dies then grip the wire and the hammer moves forward to form the head. During the forward travel of the hammer, the feed table is retracted, ready to feed material into the machine for the next nail. After the head is formed, the hammer is withdrawn and the feed table moves forward with wire for another nail. After the feed table has completed its forward travel and the header dies have gripped the wire, the cutting and pointing tools move to gether, form the point and cut off the nail and the cycle is re peated, for each nail, at every revolution of the crankshaft.

Nail machines operate at speeds varying from 150 12" spikes to over 600 cigar-box nails per minute. After nails are "cut," they are placed in rumblers, with a small amount of sawdust, and rumbled 15 or 20 minutes to remove "whiskers" and be polished and are then dumped into kegs for shipment.

Staples.

As staples are a form of nail, their manufacture is usually carried on with that of nails. They are made both from bright and galvanized wire, and in all kinds of sizes. The three different forms of points on staples are illustrated (fig. 2), the names themselves indicating the difference in the style of point. The term "presser point" simply means that the point is so sharp and fine that the staple can be stuck into the wood by simple pressure previous to being ham mered down.

The several types of machines used in the making of staples follow the same principle as in the making of the straight nail, the wire being automatically fed forward from the swift, and the operation of cutting and pointing being immediately followed by the bending of the wire into its required shape to form the staple.

(R. M. Hu.)