From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Brochure explaining the TOCCO PROCESS for hardening metal surfaces quickly and inexpensively.
Identifier | ExFiles\Box 132\4\ scan0052 | |
Date | 3rd February 1937 guessed | |
THE TOCCO PROCESS HARDENS METAL SURFACES QUICKLY, INEXPENSIVELY . WITH ACCURATE AND UNIFORM RESULTS The Ohio Crankshaft Company has been making crankshafts for leading engine manufacturers for fifteen years. In producing hundreds of thousands of shafts, it could not help but be impressed with the need for harder journals and the almost prohibitive cost of producing them by the usual, well-known methods. It seemed wasteful of both time and fuel to heat an entire crankshaft, weighing perhaps a hundred pounds, up to around 1700 degrees F.{Mr Friese} for from ten to forty hours in order to harden only the surface of the journals—perhaps one-tenth of the total surface area. Moreover, hardened fillets and counterweights were undesirable. If a new process could be evolved which would harden only the bearing surfaces and do this quickly and at small cost, a tremendous improvement would be made in manufacturing efficiency, enormous investments in heat-treating furnaces would be saved and the whole process of manufacture speeded up—with resultant savings to the users of passenger cars, trucks, buses and all machines powered by internal combustion engines. What was needed was a method of heating only that portion of any metal part which required hardening—and only the surface of that portion. When surface hardening only is required, surely it is a waste of time and money to heat the part to its very center. The new method must also be subject to accurate control. The TOCCO PROCESS of selective surface-hardening by electrical induction has been found, through years of experimental work—and latterly through actual production practice—to answer every requirement of the metallurgist and the engineer. Electricity can be accurately controlled. The TOCCO PROCESS permits the surface heating and quenching of practically all ferrous materials of cylindrical section, with the resulting hardened surface kept within close limits as to area and depth. The first application of the TOCCO PROCESS to be worked out and perfected for industrial use has been the hardening of crankshafts at the bearing surfaces. The proper hardening of crankshafts has always presented a serious problem to the manufacturers of internal combustion engines. As engines have been speeded up to increase horsepower without increasing size, harder bearing metals have been necessary. These harder bearing metals have produced more wear on the crankshaft bearings which in turn has meant increased maintenance cost, more frequent overhauling, particularly on heavy-duty engines, and excessive oil consumption. In adopting the TOCCO PROCESS of surface hardening, the manufacturers of engines not only in many cases effect a pronounced saving in the cost of manufacture by eliminating costly alloy steels and cutting down machining time, but also are assured of a superior hardened area—a longer-lived shaft. While these savings to the manufacturer are important and have been welcomed by many of the largest engine builders in the United States, still more important savings are assured their customers. Operators of buses, trucks and all heavy-duty machinery equipped with engines with TOCCO-hardened crankshafts are reporting important economies—less frequent and less costly overhauls, lower oil consumption, far longer periods of uninterrupted service. Recently passenger car manufacturers have adopted the TOCCO PROCESS to obtain the same obvious benefits and advantages. The TOCCO PROCESS has already been adopted by such outstanding and widely known manufacturers as the International Harvester Company, the General Motors Corporation, Hercules Motors Corporation, the Packard Motor Car Company, the White Motor Company, the Waukesha Motor Company, the Autocar Company, the Cummins Engine Company and many others. Image Captions: At the right is a cross section of a TOCCO-hardened crankshaft bearing, full size. The light area accurately indicates the depth to which the TOCCO surface hardening penetrates steel. At right is shown a cross section of a typical car Pittman shaft. TOCCO-hardened at roller bearing seat, thereby eliminating inner roller race. Note also cross section of steering gear Pittman arm shaft TOCCO-hardened for needle bearing seats. These drawings show the accuracy with which hardened surfaces may be confined exactly to area and depth desired. The illustration below shows the control panel which permits of automatic regulation of the TOCCO-hardening process. The KVA seconds required to produce the desired hardened area are provided by graphs compiled from experience. Once the controls are properly set, absolute uniformity of results is always assured. The illustration below shows a TOCCO-hardening installation designed and built for a leading engine manufacturer. At the right a crankshaft is shown in position for hardening pin bearings—with the inductor blocks open. At the left inductor blocks for hardening main bearings are closed, ready for hardening. The illustration above shows the inductor block with its electrical and water hose connections. Automatic control applies exactly the right amount of heat for the right number of seconds, following which the quenching is also entirely automatic. The above illustration shows a longitudinal section of a TOCCO-hardened shaft. All points shaded in the illustration are necessarily heated by any other hardening process. Only the light areas are heated by the TOCCO PROCESS. | ||