Section VI. FORGE WELDING TOOLS AND EQUIPMENT
Forge welding is a form of hot pressure welding which joins metals by heating them in an air forge or other furnace, and then applying pressure. The forge, which may be either portable or stationary, is the most important component of forge welding equipment. The two types used in hand forge welding are described below.
a. Portable Forge. The essential parts of a forge are a hearth, a tuyere, a water tank, and a blower. One type of portable forge is shown in figure 5-42. The tuyere is a valve mechanism designed to direct an air blast into the fire. It is made of cast iron and consists of a fire pot, base with air inlet, blast valve, and ash gate. The air blast passes through the base and is admitted to the fire through the valve. The valve can be set in three different positions to regulate the size and direction of the blast according to the fire required. The valve handle is also used to free the valve from ashes. A portable forge may have a handcrank blower, as shown in figure 5-42, or it may be equipped with an electric blower. The blower produces air blast pressure of about 2 oz per sq in. A hood is provided on the forge for carrying away smoke and fumes.
b. Stationary Forge. The stationary forge is similar to the portable forge except that it is usually larger with larger air and exhaust connections. The forge may have an individual blower or there may be a large capacity blower for a group of forges. The air blast valve usually has three slots at the top, the positions of which can be controlled by turning the valve. The opening of these slots can be varied to regulate the volume of the blast and the size of the fire. The stationary forges, like portable forges, are available in both updraft and downdraft types. In the updraft type, the smoke and gases pass up through the hood and chimney by natural draft or are drawn off by an exhaust fan. In the downdraft type, the smoke and fumes are drawn down under an adjustable hood and carried through a duct by an exhaust fan that is entirely separate from the blower. The downdraft forge permits better air circulation and shop ventilation, because the removal of furies and smoke is positive.
5-29. FORGING TOOLS
(1) The anvil (fig. 5-43) is usually made of two forgings or steel castings welded together at the waist. The table or cutting block is soft so that cutters and chisels caning in contact with it will not be dulled. The face is made of hardened, tempered tool steel which is welded to the top of the anvil. It cannot be easily damaged by hammering.
(2) The edges of an anvil are rounded for about 4.00 in. (102 mm) back from the table to provide edges where stock can be bent without danger of cutting it. All other edges are sharp and will cut stock when it is hammered against them. The hardy hole is square and is designed to hold the hardy, bottom, swages, fullers, and other special tools. The pritchel hole is round and permits slugs of metal to pass through when holes are punched in the stock. The anvil is usually mounted on a heavy block of wood, although steel pedestals or bolsters are sometimes used. The height of the anvil should be adjusted so that the operator’s knuckles will just touch its face when he stands erect with his arms hanging naturally.
(3) Anvils are designated by weight (i.e., No. 150 weighs 150 lb), and range in size from No 100 to No. 300.
b. Other Tools. In addition to the anvil, other tools such as hammers, sledges, tongs, fullers, flatters, chisels, swage blocks, punches, and a vise are used in forging operations.No tags for this post.