Impact extrusion

Extruding belongs to DIN 8583 for pressure forming, and thus to the family of forming processes. This is a forging that created by a single-stage or multi-stage production process both hollow and solid body.

Method

In principle, the material is caused to flow under the effect of high pressure in the process. Here, a punch pushes the blank through a shaping, reduced in cross section, mold opening - a template.

The forming is done depending on the material and shape of the component at half warm or hot temperature. In the range between 600 ° C. .. 800 ° C of Halbwarmunformen, at elevated temperatures of hot-forming, including cold forming.

It is then spoken of each cold extrusion (see cold forming ), half hot extrusion or hot extrusion (see hot forming). Particularly when cold forming a high dimensional accuracy and surface finish of the component is achieved.

, Large deformations of the material generally requires or allows only a very slight change of shape, the blank is heated prior to forming. Here the dimensional accuracy is lower and the surfaces are (required postprocessing ) due to the formation of scale rough.

The difference to the extrusion is the processing temperature and the fact that not only semi-finished strands, but also complex parts can be produced by extrusion.

Extrusion process with rigid tools is divided, depending on the flow direction in

• Forward extrusion: extrusion with material flow in the effective direction of the machine

• Backward extrusion: extrusion with material flow opposite to the direction of action of the machine. The material therefore does not flow through the die through, but through the gap between the punch and (closed ) die - opposite to the punch movement (backwards on the stamp along )

• Lateral extrusion: extrusion with material flow transverse to the direction of the machine

A combination of these three extrusion process is possible.

Furthermore, a distinction is whether in the process of full hollow or cup-shaped parts are produced. The name would then change as follows: Full - forward extrusion, hollow forward extrusion or bowl - forward extrusion.

There are also extrusion process with active media (eg hydroforming ). This includes the hydrostatic extrusion. It is a forward extrusion in which the plunger does not press directly on the workpiece, but a fluid which surrounds the workpiece. The required pressure ( 15,000-20,000 bar) is achieved by means of a pump or press.