Method of forming a splined shaft

Abstract

A method for forming splines on a metallic tube by providing a metallic tube having a known hardness corresponding to T4 temper ( 10 ); heating the metallic tube to a temperature sufficient to remove the T4 temper ( 14 ); quenching the metallic tube ( 20 ); forming splines on the metallic tube ( 30 ); and artificially aging the metallic tube, ( 32 ) where preferably the metallic tube is a 6000 series aluminum alloy.

We claim:  
     
         1 . A method for forming splines on a metallic tube, comprising the steps of: 
 (a) providing a metallic tube having properties corresponding to T4 temper;    (b) heating said metallic tube to a temperature sufficient to remove the T4 temper;    (c) quenching said metallic tube;    (d) forming splines on said metallic tube; and    (e) artificially aging said metallic tube.    
     
     
         2 . The method of  claim 1  in which (a) includes providing an aluminum alloy selected from the 2000, 5000, 6000, or 7000 series.  
     
     
         3 . The method of  claim 1  in which (a) includes selecting an alloy selected from the group consisting of 6013, 6061 and 6063; 7003, 7108 and 7029.  
     
     
         4 . The method of  claim 1  in which (a) includes providing tube formed by extrusion  
     
     
         5 . The method of  claim 1  in which (a) includes providing a drawn seamless tube.  
     
     
         6 . The method of  claim 1  in which (a) includes providing a tube formed from an elongated sheet product that is rolled in a circular configuration and then welded to form a tube.  
     
     
         7 . The method of  claim 1  in which (b) includes heating said metallic tube to a temperature between about 650° to about 1,000° F.  
     
     
         8 . The method of  claim 1  in which (b) includes heating said metallic tube in an electric induction furnace.  
     
     
         9 . The method of  claim 1  in which (b) includes heating said metallic tube in an induction coil.  
     
     
         10 . The method of  claim 1  in which (b) includes heating a said metallic tube in an induction coil that covers at least 90% of the length of said metallic tube.  
     
     
         11 . The method of  claim 1  in which (b) includes rotating said metallic tube during the heating process.  
     
     
         12 . The method of  claim 1  in which (b) includes heating only a section of said metallic tube.  
     
     
         13 . The method of  claim 1  in which (b) includes heating two or more sections of said metallic tube and there is a non-heated section between said two or more sections.  
     
     
         14 . The method of  claim 1  in which (c) includes quenching said metallic tube.  
     
     
         15 . The method of  claim 1  in which (c) includes quenching said metallic tube to temperatures approaching and to room temperature.  
     
     
         16 . The method of  claim 1  in which (c) includes quenching said metallic tube in a tank having a temperature less then about 212° F.  
     
     
         17 . The method of  claim 1  in which (c) includes quenching said metallic tube includes immersion quenching, spray quenching and mist quenching.  
     
     
         18 . The method of  claim 1  in which (c) includes quenching said metallic tube using a quenchant solution selected from the group consisting of water, polymer, air, gaseous quenchants and combinations thereof.  
     
     
         19 . The method of  claim 1  in which (d) includes forming said splines within 16 hours of said quenching if said metallic tubes are stored at room temperature.  
     
     
         20 . The method of  claim 1  in which (d) includes forming said splines within 8 hours of said quenching if said metallic tubes are stored at room temperature.  
     
     
         21 . The method of  claim 1  in which (d) includes cooling said quenched metallic tube below room temperature to retard natural aging.  
     
     
         22 . The method of  claim 1  in which (e) includes aging said tube at a temperature of at least 300° F. for at least 5 hours.