Method for manufacturing rack and hollow rack bar

Abstract

Method of fabricating a rack including: supporting a first rack bar 12 A having a first toothed part 12 a on a shaft of the first rack bar; supporting a second rack bar 12 B having a second toothed part 12 b on a shaft of the second rack bar such that an axial center line of the second rack bar coincides with an axial center line of the first rack bar; supporting a joint member 15 between the first and second rack bars such that an axial center line of the joint member coincides with the axial center lines of the first and second rack bars; rotating the joint member 15 about the axial center lines of the first and second rack bars relative to the first and second rack bars; and simultaneously bringing an end of the first rack bar and an end of the second rack bar into friction pressure welding with the joint member.

1 . A method of fabricating a rack, the method comprising:
 supporting a first rack bar having a first toothed part on a shaft of the first rack bar;   supporting a second rack bar having a second toothed part on a shaft of the second rack bar such that an axial center line of the second rack bar coincides with an axial center line of the first rack bar;   supporting a joint member between the first and second rack bars such that an axial center line of the joint member coincides with the axial center lines of the first and second rack bars;   rotating the joint member about the axial center lines of the first and second rack bars relative to the first and second rack bars; and   simultaneously bringing an end of the first rack bar and an end of the second rack bar into friction pressure welding with the joint member.   
     
     
         2 . The method according to  claim 1 , wherein a rotation of the joint member is performed by a jig for providing a rotating force and an engaging part provided for the engagement with the jig so as to prevent a sliding motion of the joint member about the axial center line of the joint member. 
     
     
         3 . A hollow rack bar comprising:
 a first rack bar that has a first toothed part on a hollow shaft of the first rack bar;   a second rack bar that has a second toothed part on a hollow shaft of the second rack bar, wherein an axial center line of the second rack bar coincides with an axial center line of the first rack bar; and   a joint member that is disposed between the first and second rack bars such that an axial center line of the joint member coincides with the axial center lines of the first and second rack bars and one end surface of the joint member is engaged with the first rack bar and the other end surface of the joint member is engaged with the second rack bar.   
     
     
         4 . The hollow rack bar according to  claim 3 , wherein the first and second rack bars have different outer diameters.