The production process of forged pipe flanges generally consists of the following steps, namely, selecting high-quality steel billets for blanking, heating, forming, and cooling after forging. The forging process methods include free forging and die forging. During production, different forging methods are selected according to the quality of the forgings and the production batch.
Free forging has low productivity, large machining allowance, simple and universal tools, and is suitable for single-piece and small-batch production. Its equipment includes air hammers, steam-air hammers and hydraulic presses, which are used to produce small, medium and large forgings respectively.
Die forging has high productivity, is easy to mechanize and automate, has high dimensional accuracy of forgings, small machining allowance, reasonable fiber tissue distribution, and longer service life.
1. Free forging
The basic processes of free forging include upsetting, drawing, punching, bending and cutting. Among them, upsetting refers to forging the billet along the axial direction to reduce its height and increase its cross-section. It is suitable for forging disc-shaped forgings such as gear billets. Drawing increases the length of the blank and reduces the cross-section, which is often used to produce shaft blanks. The punching process is to use a punch to punch through holes or non-through holes in the blank. The bending process bends the blank into a certain angle or shape, and twisting rotates one part of the blank relative to another part at a certain angle. Cutting is to split the blank or cut off the head.
2. Die forging
Die forging, that is, model forging, is to place the heated blank in the forging die of the die forging equipment for forging. The basic processes of die forging include blanking, heating, pre-forging, final forging, punching, trimming, quenching and tempering, and shot peening. Commonly used die forging equipment include die forging hammers, hot die forging presses, flat forging machines, and friction presses. Die forgings have high dimensional accuracy, small machining allowances, reasonable fiber tissue distribution, and longer service life.
Forged flanges are better quality than cast flanges, with fine crystal structure and higher strength, but the price is also correspondingly higher. Forged flanges and cast flanges are both commonly used flange manufacturing methods, and the strength requirements of the components need to be considered when choosing. If the strength requirement is not high, you can also choose to turn the flange.
Read more: Types and specifications of forged flanges or ANSI pipe flange standard
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