Material flow of a conventionally forged disc; (b) Material flow of a impactor forged disc.
The most common thought of forging equipment is the hammer and anvil. The principles behind the hammer and anvil are still used today in drop-hammer equipment. The principle behind the machine is very simple, raise the hammer and then drop it or propel it into the workpiece, which rests on the anvil. The main variations between drop-hammers is in the way that the hammer is powered; the most common being air and steam hammers. Drop-hammers usually operate in the vertical position. The main reason for this is because excess energy (energy that isn't used to deform the workpiece) that isn't released as heat or sound needs to be transmitted to the foundation. Moreover, a large machine base is needed to absorb the impacts.
To overcome some of the shortcomings of the drop-hammer the counterblow machine or impactor is used. In a counterblow machine both the hammer and anvil move and the workpiece is held between them. Here excess energy becomes recoil. This allows for the machine to work horizontally and consist of a smaller base. Other advantages include less noise, heat and vibrations. It also produces a distinctly different flow pattern. Both of these machines can be used for open die or closed die forging.
A forging press, often just called a press, is used for press forging. There are two main types: mechanical and hydraulic presses. Mechanical presses function by using cams, cranks or toggles to produce a preset (a predetermined force at a certain location in the stroke) and reproducible stroke. Due to the nature of this type of system difference forces are available at different stroke positions. Mechanical presses are faster than their hydraulic counterparts (up to 50 strokes per minute). Their capacities range from 3 to 160 MN (300 to 18,000 tons). Hydraulic presses use fluid pressure and a piston to generate force. The advantages of a hydraulic press over a mechanical press is its flexibility and greater capacity. The disadvantages are that it is slower, larger, and more costly to operate.
The roll forging, upsetting, and automatic hot forging processes all use specialized machinery.
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