770 HYDRAULICS AND ITS APPLICATIONS 



ART. 204A. STEAM-HYDRAULIC FORGING PRESS. 



By combining a steam accumulator or intensifier with the hydraulic 

 cylinders of a forging press and arranging steam actuated drawback 

 cylinders to the main ram, a type of forging press is obtained which has 

 been largely adopted of recent years on account of its flexibility, simplicity, 

 and spaed of working. Such a machine is illustrated in Fig. 383, which 

 shows a press designed for a full working power of 1,200 tons, and a 

 maximum stroke of 48 inches. At full power the stroke is about 6 inches, 

 and the machine is capable of making from 70 to 80 short strokes per 

 minute. 



The press as shown is in direct communication with the steam 

 intensifier S and a water reservoir R shown behind the steam intensifier. 

 The main cylinder C of the press is supplied with water during the idle 

 portion of the stroke from the reservoir through a large filling valve V 

 bolted directly on the top of the cylinder. The water is returned to the 

 reservoir after the pressing operation through the exhaust valve P secured 

 to the top cylinder of the steam intensifier and connected directly to the 

 reservoir. 



The movements of the press are controlled by means of a main hand 

 lever carried on a bracket on the steam intensifier, the movement of the 

 press head corresponding with the movement of the main hand lever. 

 The downward movement of the hand lever first of all exhausts the steam 

 from the under side of the drawback pistons contained in the drawback 

 cylinders DD secured to the tops of the columns of the press, thus allow- 

 ing the press head to fall until the top die reaches the work. During 

 this portion of the stroke of the main ram, the cylinder is filled with 

 water from the reservoir through the filling valve. A further downward 

 movement of the main hand lever raises the main steam admission valve 

 of the steam intensifier which forces high-pressure water from the top 

 cylinder of the intensifier into the main cylinder of the press thus 

 exerting full power on the work. The upward movement of the main 

 hand lever first opens the main exhaust valve of the steam intensifier, 

 allowing the intensifier piston to descend by gravity, and thus releasing 

 the high pressure on the main ram. The continued upward movement 

 of the main hand lever then opens the exhaust valve on the top of the 

 steam intensifier and allows the water to return from the main cylinder 

 to the reservoir, the upward movement of the press head being effected by 

 the re-admission of steam to the drawback cylinders, thereby completing 

 the cycle of operations of the press and steam intensifier. 



An auxiliary hand lever close to the main hand lever operates a small 



