VICTOR RACQUET
FRAME—1892.
Very little tubing is now imported to this country, our American makers now being able to supply all the demand, and of the highest quality. With the improved methods of manufacture has come an improvement in the quality of the steel for making tubing. It was formerly necessary to use a very soft steel in making tubing, but the American makers are now able to turn out tubing from fifteen to fifty point carbon. Right here, however, should be explained the meaning of this trade phraseology. For instance, the term “fifteen point” carbon is applied to steel which contains carbon to the extent of 15⁄100 of 1 per cent., and other numbers are used in the same way. Unquestionably the high grade carbon tubes possess a great superiority over the lower carbon grades because they possess a maximum of endurance under vibratory strain, and still are soft enough to resist the shattering effects of a heavy blow. Popular interest in tubing now centres very largely in the tubing known as the 5 per cent. nickel tubing, and its method of manufacture is described in McClure’s Magazine by Mr. Cleveland Moffett, in a visit to the Pope Tube Company’s works at Hartford, Conn. He says: “The company has recently concluded, after exhaustive experiments in the testing department, that it is possible to obtain the very best results from the use of tubing drawn from steel containing 5 per cent. nickel, an alloy of the same class as the famous nickel-steel used in armor plate constructions for the Government.” Of course, the exceptional hardness and toughness of this kind of steel occasion great difficulties in its reduction, and call for special and powerful machinery, and for special skill for all stages of manufacture. So slow and expensive has been the drawing of this nickel-steel tubing that up to date the product has been exceedingly limited, so much so that the mill has undertaken to supply only the Pope Manufacturing Company with steel of this quality. The main difficulties in working this nickel-steel come in preparing it for the draw benches. In them it is treated very much as the “fifty” carbon billets are, but before reaching them it requires almost as much handling with as many elaborate processes as the Swedish billets receive in their entire journey through the mill. The nickel-steel comes from the works of the Bethlehem Iron Company, and is rolled into plates about two feet long, one foot wide and one-tenth of an inch thick. These plates are first punched into disks about a foot in diameter in a blanking machine that weighs four tons, and bites through the cold steel as a housewife stamps out biscuits. These disks are then put through a number of hydraulic presses, even heavier than the blanking machine, and are forced through dies by powerful rams. The first operation brings the disks to the shape of a shallow basin; the next makes it an elongated cup; the next makes it still longer, and so on, until finally it is reduced to the form of a tube, two feet or more in length. Then the rounded end of the tube is sliced off, and the nickel-steel is in the form of a billet ready for the draw benches.
“Simple enough these processes seem when one sees them going smoothly; but it took months of patient toil, with many mistakes and disappointments, before the company learned the right way of ‘cupping’ these disks into billets. And today the museum of the tube department bears record of the many failures in cups crushed into fantastic shapes, some with ragged sides, and in tubes of nickel-steel deformed in many ways and torn apart in drawing.”
MAKING DROP FORGINGS.
A drop-forging differs from a hand-made forging because it is made from a bar of steel suitable for the purpose required and formed in dies placed in drop hammers, this bar of steel having been previously heated to the proper degree in a furnace adjacent to the drop hammer which is used. A drop hammer may be described as follows: The main part of the machine consists of a heavy anvil, or base, weighing from 7,000 to 30,000 pounds, depending on the size of the hammer. To this is attached two vertical uprights, between which the head or ram of the hammer works. On the top of these uprights is the lifting mechanism, a board being attached to the hammer and the rolls that revolve in the head act upon this board and lift the weight by friction. In the base first mentioned are fastened the lower dies, the upper die being attached to the hammer. In these dies the impression for the forging wanted is cut by skilled mechanics, the dies afterward being tempered to make them as hard and durable as possible. The piece of steel having already been heated to a white heat, is held on the lower die by the workman, who then operates the drop hammer by means of a foot treadle, the hammer with the upper die dropping by gravity and forcing the heated metal into the impressions cut in the dies.
THE STEARNS.