B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
B21C23/00—Extruding metal; Impact extrusion
B21C23/02—Making uncoated products
B21C23/04—Making uncoated products by direct extrusion
Procede pour former des structures superficielles sur une matrice, notamment pour la production de gravures estampees sur des panneaux comprimes en matiere plastique ou sur des stratifies de matiere plastique