Modern precise high-power water-cooling systems for press quenching

Demand for extrusions in transport applications is increasing rapidly. The extrusions must be strong, light, crashworthy and may have to undergo hydroforming. This implies low wall thicknesses (1-21⁄2 mm) in strong alloys that need very fast quenching to obtain the required T4 temper. Crashworthiness – the ability to absorb a lot of energy in crushing deformation – demands very uniform properties throughout the section, and so does hydroforming. Various systems of water or air/water jets, with and without scanning, with and without arrangements for precisely aiming the jets, have proved effective for less difficult alloys in wall thicknesses down to 3 mm. These are unsuitable for the new types of transport extrusions, either inducing physical distortion or non-uniform mechanical properties. A novel cooling system that satisfies the new requirements uses laminar water jets of 50-250 μm diameter in a densely packed array of up to 10/cm2. These are arranged in modules whose position and direction of aim can be adjusted relative to the part of the extrusion they cool, assuring linear cooling of all parts of the section at up to 500 K/s. The array of modules is very compact and not expensive. A sophisticated system of water microfiltration ensures that the fine nozzles do not become blocked.