continuous+rolling+method

n < prod> (Schneckenradherstellung) ■ tangential feed method

n < prod> (Gewindewalzen) ■ through-feed thread-rolling; through-feed rolling; thru-feed rolling US ; continuous rolling rare ; end-feed rolling rare

SUBJECT AREA: Metallurgy

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Junghans was of the family that owned Gebrüder Junghans, one of the largest firms in the German watch-and clockmaking industry. From 1906 to 1918 he served in the German Army, after which he took a course in metallurgy and analytical chemistry at the Technical High School in Stuttgart. Junghans was then given control of the brassworks owned by his family. He wanted to make castings simply and cheaply, but he found that he lacked the normal foundry equipment. By 1927, formulating his ideas on continuous casting, he had conceived a way of overcoming this deficiency and began experiments. By the time the firm was taken over by Wieland-Werke AG in 1931, Junghans had achieved positive results. A test plant was erected in 1932, and commercial production of continuously cast metal followed the year after. Wieland told Junghans that a brassfounder who had come up through the trade would never have hit on the idea: it took an outsider like Junghans to do it. He was made Technical Director of Wielands but left in 1935 to work privately on the development of continuous casting for all metals. He was able to license the process for non-ferrous metals during 1936–9 in Germany and other countries, but the Second World War interrupted his work; however, the German government supported him and a production plant was built. In 1948 he was able to resume work on the continuous casting of steel, which he had been considering since 1936. He pushed on in spite of financial difficulties and produced the first steel by this process at Schorndorf in March 1949. From 1950 he made agreements with four firms to work towards the pilot plant stage, and this was achieved in 1954 at Mannesmann's Huckingen works. The aim of continuous casting is to bypass the conventional processes of casting molten steel into ingots, reheating the ingots and shaping them by rolling them in a large mill. Essentially, in continuous casting, molten steel is drawn through the bottom of a ladle and down through a water-cooled copper mould. The unique feature of Junghans's process was the vertically reciprocating mould, which prevented the molten metal sticking as it passed through. A continuous length of steel is taken off and cooled until it is completely solidified into the required shape. The idea of continuous casting can be traced back to Bessemer, and although others tried to apply it later, they did not have any success. It was Junghans who, more than anybody, made the process a reality.

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SUBJECT AREA: Aerospace, Steam and internal combustion engines

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He was the son of Francis Barber, coalmaster of Greasley, and Elizabeth Fletcher. In his will of 1765. his uncle, John Fletcher, left the bulk of his property, including collieries and Stainsby House, Horsley Woodhouse, Derbyshire, to John Barber. Another uncle, Robert, bequeathed him property in the next village, Smalley. It is clear that at this time John Barber was a man of considerable means. On a tablet erected by John in 1767, he acknowledges his debt to his uncle John in the words "in remembrance of the man who trained him up from a youth". At this time John Barber was living at Stainsby House and had already been granted his first patent, in 1766. The contents of this patent, which included a reversible water turbine, and his subsequent patents, suggest that he was very familiar with mining equipment, including the Newcomen engine. It comes as rather a surprise that c.1784 he became bankrupt and had to leave Stainsby House, evidently moving to Attleborough. In a strange twist, a descendent of Mr Sitwell, the new owner, bought the prototype Akroyd Stuart oil engine from the Doncaster Show in 1891.

The second and fifth (final) patents, in 1773 and 1792, were concerned with smelting and the third, in 1776, featured a boiler-mounted impulse steam turbine. The fourth and most important patent, in 1791, describes and engine that could be applied to the "grinding of corn, flints, etc.", "rolling, slitting, forging or battering iron and other metals", "turning of mills for spinning", "turning up coals and other minerals from mines", and "stamping of ores, raising water". Further, and importantly, the directing of the fluid stream into smelting furnaces or at the stern of ships to propel them is mentioned. The engine described comprised two retorts for heating coal or oil to produce an inflammable gas, one to operate while the other was cleansed and recharged. The resultant gas, together with the right amount of air, passed to a beam-operated pump and a water-cooled combustion chamber, and then to a water-cooled nozzle to an impulse gas turbine, which drove the pumps and provided the output. A clear description of the thermodynamic sequence known as the Joule Cycle (Brayton in the USA) is thus given. Further, the method of gas production predates Murdoch's lighting of the Soho foundry by gas.

It seems unlikely that John Barber was able to get his engine to work; indeed, it was well over a hundred years before a continuous combustion chamber was achieved. However, the details of the specification, for example the use of cooling water jackets and injection, suggest that considerable experimentation had taken place.

To be active in the taking out of patents over a period of 26 years is remarkable; that the best came after bankruptcy is more so. There is nothing to suggest that the cost of his experiments was the cause of his financial troubles.

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SUBJECT AREA: Metallurgy

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Wöhler, the son of a schoolteacher, was born at Soltau on the Luneburg Heath and received his early education at his father's school, where his mathematical abilities soon became apparent. He completed his studies at the Technical High School, Hannover.

In 1840 he obtained a position at the Borsig Engineering Works in Berlin and acquired there much valuable experience in railway technology. He trained as an engine driver in Belgium and in 1843 was appointed as an engineer to the first Hannoverian Railway, then being constructed between Hannover and Lehrte. In 1847 he became Chief Superintendent of rolling stock on the Lower Silesian-Brandenhurg Railway, where his technical abilities influenced the Prussian Minister of Commerce to appoint him to a commission set up to investigate the reasons for the unusually high incidence of axle failures then being encountered on the railways. This was in 1852, and by 1854, when the Brandenburg line had been nationalized, Wöhler had already embarked on the long, systematic programme of mechanical testing which eventually provided him with a clear insight into the process of what is now referred to as "fatigue failure". He concentrated initially on the behaviour of machined iron and steel specimens subjected to fluctuating direct, bending and torsional stresses that were imposed by testing machines of his own design.

Although Wöhler was not the first investigator in this area, he was the first to recognize the state of "fatigue" induced in metals by the repeated application of cycles of stress at levels well below those that would cause immediate failure. His method of plotting the fatigue stress amplitude "S" against the number of stress cycles necessary to cause failure "N" yielded the well-known S-N curve which described very precisely the susceptibility to fatigue failure of the material concerned. Engineers were thus provided with an invaluable testing technique that is still widely used in the 1990s.

Between 1851 and 1898 Wöhler published forty-two papers in German technical journals, although the importance of his work was not initially fully appreciated in other countries. A display of some of his fracture fatigue specimens at the Paris Exposition in 1867, however, stimulated a short review of his work in Engineering in London. Four years later, in 1871, Engineering published a series of nine articles which described Wöhler's findings in considerable detail and brought them to the attention of engineers. Wöhler became a member of the newly created management board of the Imperial German Railways in 1874, an appointment that he retained until 1889. He is also remembered for his derivation in 1855 of a formula for calculating the deflections under load of lattice girders, plate girders, and other continuous beams resting on more than two supports. This "Three Moments" theorem appeared two years before Clapeyron independently advanced the same expression. Wöhler's other major contribution to bridge design was to use rollers at one end to allow for thermal expansion and contraction.

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