(1) Free forging. Free forging is generally performed between two flat dies or dies without a die cavity. The tools used in free forging have simple shapes, high flexibility, short manufacturing cycle and low cost. However, the labor intensity is high, the operation is difficult, the productivity is low, the quality of the forgings is not high, and the machining allowance is large. Therefore, it is only suitable for use when there are no special requirements for the performance of the parts and the number of parts is small. For large forgings, free forging is mainly used as a billet making process. The free forging billet process can forge the billet into a ladder-shaped bar, or use upsetting or flattening methods to make the billet into simple shapes such as a round cake shape or a rectangle.
(2) Open die forging (die forging with burrs). The blank is deformed between two modules with carved mold cavities, and the general part is restricted inside the mold cavity. The excess metal flows out from the narrow gap between the two molds, forming burrs around the forging. Under the resistance of the mold and the surrounding burrs, the metal is forced into the shape of the mold cavity.
(3) Closed die forging (no burr die forging). During the closed die forging process, no transverse burrs are formed perpendicular to the direction of die movement. The die cavity of a closed forging die has two functions; one part is used to shape the blank, and the other part is used to guide.
(4) Extrusion die forging. There are two types of die forging using extrusion method: forward extrusion die forging and reverse extrusion die forging. Extrusion die forging can produce a variety of titanium rings. Forgings with high geometric dimensional accuracy and denser internal structure can be obtained.
(5) piercing punches make the metal flow outward from the center of the mold cavity to fill the mold cavity. There are no burrs of ordinary forgings on the parting line of cylindrical parts.
(6) Partial die forging. In order to forge large-scale integral die forgings on existing hydraulic presses, segmented die forging methods such as segmented die forging and pad die forging can be used. The characteristic of the partial die forging method is that the titanium cake is processed section by section, one part at a time, so the tonnage of the equipment required can be very small. Generally speaking, this method can be used to process extra large forgings on medium-sized hydraulic presses.
(7) Isothermal die forging. Before forging, the mold is heated to the forging temperature of the blank, and the temperatures of the mold and the blank are kept consistent during the entire die forging process, so that large deformation can be obtained under the action of small deformation force. Isothermal die forging is very similar to isothermal superplastic die forging. The difference is that in the latter, before die forging, the blank must be superplasticized to make it have fine equiaxed grains.
