PROCESS OF MACHINE OR UPSET FORGING

Forging of the ring and rod types with all kinds of heads and shoulders, such as bolts, nuts, washers and collars and pinion-gear blanks, etc. can be conveniently produced in the forging machine.

Machine or upset forging consists of applying length wise pressure to a hot bar held between grooved dies to enlarge some section or sections, usually the end. Not only bulging, but piercing can also be done by the machine forging method. In this method the metal is displaced from the interior and made to flow around the outside, for the full length of the blank when necessary. Careful gathering of a large volume of metal on the end results in controlled grain structure, with dense fiber for maximum length.

Mostly a through-bore is drilled longitudinally through the die for the feeding of bar stock. Further, the die is split up to into halves which form two jaws ; one of them is fixed, whereas the other one can be opened to admit the blank. Mostly, these jaws also serve for clamping the workpiece to be upset.

The heated end of a bar stock is inserted into the stationary die up to the stop. At this time, the punch is in its left position. Next the movable die grips the bar stock and, at the same time, an impression is formed in the closed dies for shaping the projecting stock; the stop is automatically retraced to its idle position. Then the punch advances to upset the bar and forms the finished forging and finally, the movable die and the punch are withdrawn to their initial position. The rod and forging are shifted to the next pass where the forging is cut off.

Horizontal forging machines operate at a high rate. They have an output of from 400 to 600 forgings per hour and develop a forging force of from 100 to 3000 tons.

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