Definition: It is a machining method of forging in order to obtain certain mechanical properties, shape and size by applying pressure to metal blank by forging machine.
Forging can eliminate the loose casting state of metal and weld holes. The mechanical properties of forging are generally better than those of the same material.The important parts with high load and severe working conditions in the machinery, in addition to the simple shape of the available rolling plates, profiles or welding parts, are mostly used forgings.
Forging according to the forming method can be divided into:
1. open mould forging (free forging).Using the impact force or pressure to make the metal in the upper and the two lower two hold iron (anvil block) have deformation to obtain the required forging parts, mainly contains manual forging and mechanical forging.
2. closed mode forging:Forgings are made of metal billet under pressure and deformation in the forging mould bore with a certain shape, which can be divided into die forging, cold heading, rotary forging, extrusion, etc.According to the deformation temperature, forging can be divided into hot forging (the processing temperature is higher than the recrystallization temperature of the blank metal), warm forging (lower than the recrystallization temperature) and cold forging (normal temperature).
Identification of castings and forgings
1. The surface structure of the forging shall be of fine density, and the surface of the casting shall be thicker, while the machining surface of the forging shall be brighter.
2, cast iron section is gray, and forged steel section is silver.
3. Listen to the sound, the forging is dense, the sound is clear after striking, and the casting sound is dull.
4, grinding with a grinder to see the two sparks are different (forging is brighter).