FORGING FURNACE

Evening Star, Issue 19843, 17 April 1928, Page 2

FORGING FURNACE

HEATED ELECTRICALLY Designed for heating steel automobile parts for upsetting purposes, a new form of electric metal boater has been installed in a Detroit factory (states ‘Electrics’). The machine is very similar to an electric rivet heater, but handles ranch larger work- Current is passed directly through the piece to be heated, which is clamped between two pairs of contacts. The maximum size piece heated is .IJi ll long. A current of about 15,000 amps, is applied at a pressure of 1 to 1J volts. The machine will take five pieces at a timei.e., there arc five sots of contacts—and the maximum demand when running at full capacity is 72 kw.; the average demand, of course, is much less. Some preliminary ditijcultics in the operation of the machine have been overcome, and an extended trial oyer twelve months shows this application of electric heating to be entirely .successful. The electric heater was adopted after throe gas furnaces ol different designs had been tried without success. The contacts arc simply tangential ones, no attempt being made to make them the same shape as the heated piece. The contacts wore made ol heavy copper, not water cooled; they arc adjustable for heat length of about 2in to 7in. One man operates the beater, another the upsetting machine. A second heater of tiic same size is now being installed, and one man will operate the two heaters.

An outstanding feature of the electric method is the comparative coolness and absence of fumes. Another advantage is that the heater does not have to bo started in the morning two on three hours before time to start work. Also it is shut off dead when work is stopped at the end of the day. 'the equipment heats about 41b of metal per kw. hour. This means actual metal heated between contacts. Each piece takes about 2imin to heat, compared with 30min per piece in a gas furnace. The pieces are removed -after heating by judgment of the operator. Application of automatic thermal control was contemplated—one reason being that the desirable forging temperature, 2,loodcg F., was close to the burning-np temperature, 2,450 deg F.—but was considered to be too complicated awl expensive. A control based on the time a piece is clamped between the contacts to give the proper forging beat is tieing considered.