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
B21C23/18—Making uncoated products by impact extrusion
B21C23/186—Making uncoated products by impact extrusion by backward extrusion
B—PERFORMING OPERATIONS; TRANSPORTING
B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
B21K21/00—Making hollow articles not covered by a single preceding sub-group
B21K21/04—Shaping thin-walled hollow articles, e.g. cartridges
Procede pou obtenir l'effet diamante dans un produit manufacture en metal precieux, comme en particulier une chaine avec maillons du type creux et chaine ainsi obtenue