Pressing Frames for Heavy Vehicles
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ASINGLE-ACTION erankless press, having a capacity of 2,000 tons, has recently been completed_ at the Elswick Works of Vickers-Armstrongs, Ltd., Newcastle-on-Tyne, for the manufacture of chassis frames of heavy vehicles. It is one of the largest mechanical presses built by the company in conjunction with the Clearing Machine Corporation, Chicago, U.S.A.
The machine is 35 ft. high overall, 25 ft. between uprights and weighs 220 tons. It is notable not only for its size, but is an outstanding example of modern press design applied to the requirements of high capacity and accurate operation.
The separate frame members, comprising bed, uprights and crown, are of all-welded steel construction, the largest fabrication being that of the bed, which alone weighs 67 tons.
Four massive steel tie rods sedure the frame members; and the slide, which is also fabricated, is suspended from two plungers housed in the crown, through which they are guided in bronze bearings. Precise alignment is assured by the provision of four individually adjustable gibs.
The plungers are operated by bronze-lined steel eccentrics, which are cast integral with the driving gears. These gears, together with their driving pinions, all cut from solid, are totally enclosed in the crown, where they run in an oil bath.
Belt Drive Drive from the operating motor is by V belt to a balanced flywheel driving a friction-type air-operated electrically controlled clutch. All main bearings are bronze-lined steel castings welded to the steel-plate fabrication of the crown, and lubricated by an electrically driven highspeed pump drawing its supply from the crown oil bath.
A power-operated slide adjustment by an independent 10 li.p. motor, located within the slide, operating through bevel gears and massive adjusting screws, gives a maximum adjustment of 20 ins.
Five air-operated die cushions are accommodated in the bed. These cushions are guided for the full length of stroke. Each is provided with bronze wear strips and is capable of absorbing a pressure of approximately 80 tons at a working pressure of 100 lb. per sq. in., giving a total cushion capacity of 400 tons.
Slide and die counterbalance is provided by four counterbalance cylinders located in the crown.
The all-electric clutch control embodies a rotary-type cam limit switch. contactor panel and selector switches, by the use of whichit is possible to control the press through four cycles of operation by means of push buttons