Process for manufacturnig an internally cooled valve having a cooling structure, and valve manufactured by said method

Abstract

The invention relates to a process for manufacturing an internally cooled valve, said process involving providing an externally at least partly cylindrical semifinished product ( 2 ), creating or increasing the depth of an at least partly cylindrical cavity in the semifinished product ( 2 ) in a hot-working procedure using a male die such that a valve blank is formed; during the hot-working procedure, a recess on an end face of the male die forms a structure on the bottom of the cavity.

1 - 11 . (canceled) 
     
     
         12 . A method for producing a valve blank for an internally cooled valve, comprising providing a semifinished product having an at least partially cylindrical exterior, and creating an at least partially cylindrical cavity in the semifinished product by heat forming, using a stamp, thus producing a valve blank, wherein the hot forming encompasses backward extrusion, wherein a structure is formed on a base of the cavity during the hot forming via a recess at n end face of the stamp. 
     
     
         13 . The method for producing a valve blank according to  claim 12 , wherein the structure includes cooling ribs that extend in a circular or star shape. 
     
     
         14 . The method for producing a valve blank according to  claim 12 , wherein the structure includes pins, cones, or truncated cones that act as cooling elements. 
     
     
         15 . The method for producing a valve blank according to  claim 12 , wherein the structure includes blades that are able to set a coolant in a valve into rotation. 
     
     
         16 . The method for producing a valve blank according to  claim 12 , wherein a valve head is formed onto the valve blank during the hot forming. 
     
     
         17 . A method for manufacturing an internally cooled valve, wherein after the valve head is formed according to  claim 16 , a diameter of the valve blank next to the valve head is reduced in the axial direction in order to form a valve stem. 
     
     
         18 . The method for manufacturing an internally cooled valve according to  claim 17 , wherein the valve stem is formed by rolling or rotary swaging. 
     
     
         19 . The method for manufacturing an internally cooled valve according to  claim 17 , wherein the valve stem is formed by rolling or cross wedge rolling. 
     
     
         20 . An internally cooled valve that is manufactured using a method according to  claim 12 . 
     
     
         21 . The method for manufacturing an internally cooled valve according to  claim 17 , wherein the valve stem is formed by hot hammering or cold hammering on a mandrel. 
     
     
         22 . The method for manufacturing an internally cooled valve according to  claim 19 , wherein the valve stem is formed by rolling on a mandrel.