TUBE MAKING.
The air is filled with the vocabulary of the bicycle makers and their agents and salesmen. Every one of them talks of cold drawn weldless steel tubing, drop forgings, stampings and brazing. Their catalogues and their advertisements teem with the same thing, and the cyclist who has heard and read these terms necessarily feels as if he would like to know what they all mean. Tube in its original shape consists of a solid billet of Swedish steel, this being the only quality that can be used. When the tube is made from a solid, the billet is about four inches in diameter and six inches in length. When it is made from a hollow ingot, a piece about three feet long and about four inches in diameter, with about half-inch walls, is used. These pieces are cast. When solid billet is used, the core is practically either pushed out or drilled out to produce a rough tube. This is done while hot, and the hot pressure is continued until the tube is about four or five feet long; the diameter then is about 2½ inches, with proportionate thickness of walls.
The tube is then taken to the cold draw benches. Draw benches, so called, are of two kinds, either operated by hydraulic or chain power. In the case of the hydraulic bench, an immense plant is required to produce the enormous pressure required, approximated at about 2,500 pounds to the square inch. This power is applied through a cylinder three or four inches in diameter and about eighteen feet long, operating a piston. The power is so arranged that the piston can be made to either go forward or backward. The operator crushes down one end of the tube to be drawn, to make it small enough to pass through a die, and the tube is then grasped in a grip held by the piston. As the bench moves the tube passes through the die and becomes smaller. Inside of the tube and flush up against the die is kept a mandrel, over which the shell of the tube passes in going through the die. This mandrel is placed in the tube to keep the shell or gauge from thickening up, and also to produce a thinner gauge when required. Each operation reduces the diameter about an eighth of an inch. It is not possible to reduce the gauge at the most more than 5⁄1000 of an inch at a time, and this is very severe treatment. Between each drawing in the cold process the tubes are annealed, the operation of drawing hardening them. After annealing they are pickled in a solution of acid and water. The tubes are then washed in clear water; then they are immersed in oil, and are ready to be drawn over again. This process is repeated until such time as the tube reaches the desired gauge and outside diameter. The tubes are then straightened and the ends cut off, and they are ready for delivery.
The Pope Tube Company hold the exclusive license in the United States, however, for a process of annealing steel tubes in iron cylinders about a foot in diameter and 12 feet in length. These retorts hold about 100 to 150 tubes, and being charged with these are sealed up at the end and placed in a furnace. The advantage of this method consists in that the tubes being placed in the retort do not come in direct contact with the flames, which form a scale upon the surfaces and require the subsequent operation of pickling the tubes in large vats of acid in order to remove the scale. This process of annealing in the retorts usually takes about forty minutes, and necessarily in the process of drawing a tube before it reaches the proper size it must go through the process of annealing from five to eight, or even ten, times before being finished. The only difference between the operation of a hydraulic draw bench and of a chain bench is that in the chain bench there is a continuous chain, operated by steam power, and the grip is so arranged that it will catch in any link desired. Seamless tubes are made from 1⁄32 to 10 inches in diameter. Gauge, or thickness of shell, is measured according to the standard British wire gauge. Bicycle tubes run from 26 to 10 gauge. The standard gauges used in bicycle construction for 1898 run from about 16 to 22.
CLEVELAND
FORK CROWN.
It takes fifty thicknesses of 22-gauge tubing to make an inch. Experts in the trade say that tapered gauge tubing is the coming thing in bicycle construction. By this term is meant that style of tubing which is heavy where strain is greatest and light in weight where there is not so much strain. The outside diameter of the tubing, however, remains the same all the way through. This is opposed to the ordinary even-gauge tubing or tubing of uniform thickness of shell. Weldless steel fork sides are made out of the straight tubing already described, the first operation consisting in drawing the tube to the proper tapered design. It is then, by a series of operations, brought to the flattened or oval shape. Other operations are also necessary to produce the required curve in the fork. The smaller end which receives the axle of the wheel is flattened together by another operation. The making of a weldless steel fork side usually takes from five to seven operations, according to the shape desired.
The Mannesman tubing, which is made in Germany and was the first kind known to be used for bicycles in this country, is made by an entirely different method from any other. Until recently the making of tubing was so restricted that those owning tubing mills were very secretive about their processes, and not one cycle rider or manufacturer out of a hundred has ever seen the material made out of which the frame of his machine is constructed. They begin with the billet of steel like the English-American makers, but it is not exactly the same material. They do not use the Swedish steel, but a metal turned out by themselves. It is, however, a soft form of steel, like the Swedish or Norway article. The billets are made up in lengths of three feet and are about two inches in diameter. First the metal is heated and then put into a rolling machine. This is a special device used only in their plant under patents. It consists not only of the ordinary roller but of two conical rolls, and they are set together on axles, which instead of being parallel are oblique. The points of these conical rollers are in opposite directions, of course, and by the peculiar action thus obtained the outside skin of the heated metal is peeled and spun over the inside in a spiral fashion, much as a rope is twisted. It is practically a huge spinning with hot metal. After this single rolling process, the new formed tube is subjected to two drawings in a mandrel, in practically the same fashion that American tubing is treated, until it is reduced to the required diameter and gauge.
A billet of the size described makes a piece of tubing an inch and a quarter in diameter, of gauge fourteen, or about one-twelfth of an inch thick. An essential difference between this process and the one used in this country is that here there are only two drawings and no annealing, where other processes necessitate a dozen and sometimes a score of solid drawings. It is claimed that with only two drawings the fibre of the steel is better preserved. The fibres are not shortened or made brittle, as they are by repeated drawings.
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.”