Patent GB-757526-A (GB)
Title: Improvements in or relating to apparatus for forging crank-shafts
Inventor: CLEGHORN GEORGE SHEWAN
IPC: B21K1/08
Filed: 1953-11-23
Abstract: 757,526. Forging crank-shafts. COMPAGNIE DES ATELIERS ET FORGES DE LA LOIRE ST.-CHAMOND, FIRMINY, ST.-ETIENNE ET J. HOLTZER, ENGLISH STEEL CORPORATION, Ltd., and CLEGHORN, G. S. Sept. 30, 1954 [Nov. 23, 1953], No. 32428/53. Class 83 (4). Apparatus for forging crank-shafts comprises end dies 5, 6 adapted to receive spaced portion of a workpiece I and movable towards each other so as to upset parts of the workpiece disposed between the dies, a transverselymovable centre tool 9, 9a adapted to grip an intermediate portion 1a of the workpiece and force it out of alignment with the axis of the workpiece, separate hydraulic means for operating the end dies and the centre tool and means for synchronizing the movements of the end dies and the centre tool. The end dies comprise lower halves 5, 6 mounted on horizontally movable cradles 4, 4a and upper halves 5a, 6a suspended through members 27, 28 from pistons 26 movable in hydraulic cylinders 26a in a fixed head 10. The die halves 5a, 6a are movable horizontally relative to the parts 27 when the latter have been lowered by the pistons 26 to clamp the. workpiece between the die halves 5, 5a, 6, 6a, such movement being facilitated by rollers 29. The end die 6, 6a is adapted to receive a formed crank throw and position it angularly and axially. The cradles 4, 4a are moved towards each other by pistons 11a, 12a, Fig. 5, working in cylinders 11, 12, attached to the cradle 4 and connected by rods 11b, 12b to bosses 13 on the cradle 4a. Universal joints may be provided between the rods and bosses to compensate for uneven wear on the cradle slides. Pressure liquid is supplied to the cylinders 11, 12 through pipes 17, 16 from a differential cylinder device 14, 14a containing a differential piston 15, 15a of which the area of the piston 15a is equal to the annular working area of the piston 15 whereby an equal volume of pressure liquid is forced into each cylinder 11, 12, thereby preventing slewing of the cradles. Pressure liquid may be admitted to the cylinders 11, 12 through pipes 17a for retracting the cradles or separate drawback cylinders and pistons may be provided. To ensure that the rate of movement is the same for both cradles and their end dies, auxiliary cylinders 18, 18a, Fig. 2, are provided on the bed 2 below the cradles and contain double-acting pistons 19 whose piston-rods 19a are secured to the cradles. The right-hand end of cylinder 18 is connected by a pipe to the left-hand end of cylinder 18a and vice versa, Fig. 6 (not shown), and connections are provided for make-up of liquid. Alternatively the auxiliary cylinders may be secured to the cradles and the pistonrods to the bed. Instead of the auxiliary cylinders, a rack-and-pinion mechanism may be used to ensure uniform movement of the cradles. The centre tool is in two halves 9, 9a of which the lower half 9 is actuated by an hydraulic piston 7 in a cylinder 8 and the upper half 9a is supported against the workpiece to form a cushion by an hydraulic piston 23.working in a cylinder 24. The cylinders 7, 24 may be reversed so that the working stroke of the centre tool 9 is downwards. Draw-back pistons 25 and 30, Figs. 3, 4 (not shown), are provided for the centre half tool 9a and the upper end half dies 5a, 6a. The head 10 is hingedly supported at 31 on columns 22 whereby it can be swung upwardly by a winch to facilitate insertion of a workpiece, withdrawal of the forged crank-shaft or changing of tools. The head is secured in its horizontal position by parallel or taper locking- pins which may be withdrawn by hydraulic or pneumatic motors. Alternatively the bed 2 may be adapted to traverse from under the head 10 or the cradles may be given an increased outward stroke so that they may be withdrawn clear of the head. The stroke of the centre tool is synchronized with that of the end dies by racks connected to the respective parts and operating a spur gear differential mechanism, Figs. 7, 8 (not shown), the output of which is connected to a valve controlling the flow of pressure liquid to the hydraulic mechanism of the centre tool.