3. Forging (I)

1 3. Forging (I). Bong-Kee Lee School of Mechanical Systems Engineering Chonnam National University Overview ( Forging ).. ( ) . , .. School of Mechanical Systems Engineering Forging ( Forging ).. : , , , , .. (a) Schematic illustration of the steps involved in Forging a knife. (b) Landing-gear components for the C5A. and C5B transport aircraft, made by Forging . (c) General view of a 445 MN (50,000 ton) hydraulic press. School of Mechanical Systems Engineering Forging ( Forging ).. , .. (a) Casting, (b) machining from a blank, and (c) Forging School of Mechanical Systems Engineering Forging ( Forging ).. ( ), ( . ).. (net-shape forming) (near-net shape forming) (precision Forging ) .. School of Mechanical Systems Engineering Forging (open-die Forging ).. Process Advantages Limitations Limited to simple shapes; difficult to hold Simple and inexpensive dies; wide range of close tolerances; machining to final shape Open die part sizes; good strength characteristics; necessary; low production rate; relatively poor generally for small quantities utilization of material; high degree of skill required Relatively good utilization of material.

2 Generally better properties than open-die High die cost, not economical for small Closed die forgings; good dimensional accuracy; high quantities; machining often necessary production rates; good reproducibility Machining to final shape necessary; parts with Blocker Low die costs; high production rates thick webs and larger fillets Requires much less machining than blocker Conventional type; high production rates; good utilization of Higher die cost than blocker type material Close dimensional tolerances; very thin webs High Forging forces, intricate dies, and Precision and flanges possible; machining generally not provision for removing Forging from dies necessary; very good material utilization School of Mechanical Systems Engineering Forging (open-die Forging ). (upsetting), (flat-die Forging ).. (barreling). , .. School of Mechanical Systems Engineering Forging (open-die Forging ). (cogging).. ( , bite) . (a) Schematic illustration of a cogging operation on a rectangular bar.

3 (Blacksmiths use this process to reduce the thickness of bars by hammering the part on an anvil. Reduction in thickness is accompanied by barreling.). (b) Reducing the diameter of a bar by open-die Forging (c) The thickness of a ring being reduced by open-die Forging School of Mechanical Systems Engineering Forging (impression-die Forging ).. (cavities) . (ductility) .. (flash): .. School of Mechanical Systems Engineering Forging (impression-die Forging ).. (parting line). (flash). (draft angle). School of Mechanical Systems Engineering Forging (impression-die Forging ). (die insert).. Die inserts used in Forging an automotive axle housing School of Mechanical Systems Engineering Forging (impression-die Forging ). (preforming operations). (blank) .. (preform) : , , .. (fullering): . (edging): . School of Mechanical Systems Engineering Forging (impression-die Forging ).. : . (blocking): (blocker die).. (trimming). ( ).. School of Mechanical Systems Engineering Forging (impression-die Forging ).

4 (trimming).. School of Mechanical Systems Engineering Forging (closed-die Forging ).. : . : . School of Mechanical Systems Engineering Forging (precision Forging ).. , , .. School of Mechanical Systems Engineering Forging . : slug, billet, or preform ( ) . ( ) ( ) .. (trimming, machining, or grinding).. , .. School of Mechanical Systems Engineering Forging . (coining). , , .. , .. School of Mechanical Systems Engineering Forging . (heading) (upset Forging ).. , , . (header): . School of Mechanical Systems Engineering Forging . (piercing).. (piercing force) (a) , (b) . , (c) . School of Mechanical Systems Engineering Forging .. School of Mechanical Systems Engineering Forging . (hubbing).. (orbital Forging ). School of Mechanical Systems Engineering Forging . (incremental Forging ).. (isothermal Forging ).. School of Mechanical Systems Engineering Forging . (rotary swaging). School of Mechanical Systems Engineering Forging . (tube swaging).

5 (internal diameter) .. School of Mechanical Systems Engineering Forging (forgeability).. , . (upsetting) : . - (hot-twist) : . : , , , .. : , , , . School of Mechanical Systems Engineering Forging (defects). (crack) .. School of Mechanical Systems Engineering Forging (defects).. School of Mechanical Systems Engineering Forging . , , - (stroke) .. Equipment m/s Hydraulic press Mechanical press Screw press Gravity drop hammer Power drop hammer Counterblow hammer School of Mechanical Systems Engineering Forging . (hydraulic press).. (mechanical press). (crank press) (knuckle joint press). , . ( ). School of Mechanical Systems Engineering Forging . (screw press).. , .. (hammer).. (power hammer, power drop hammer): .. , . School of Mechanical Systems Engineering Forging . (counterblow hammer).. - - . (HERF, high-energy-rate Forging ).. School of Mechanical Systems Engineering