Method of manufacturing cam piece for continuously variable valve duration and cam piece manufactured therefrom

Abstract

A method of manufacturing a cam piece for a continuously variable valve duration and a cam piece manufactured therefrom, and more particularly, to material and heat treatment conditions of a cam piece, may include manufacturing a cam piece by casting; heating the cam piece; maintaining a heating temperature; and salt-bathing the cam piece, in which the cam piece includes 3.2 to 4.2 wt % of carbon (C), 2.2 to 3.4 wt % of silicon (Si), and the balance iron (Fe), and may have a carbon equivalent value of 4.4 to 4.6.

1 - 8 . (canceled) 
     
     
         9 . A cam piece for a continuously variable valve duration, comprising 3.2 to 4.2 wt % of carbon (C), 2.2 to 3.4 wt % of silicon (Si) and balance iron (Fe), wherein the cam piece has a carbon equivalent value of 4.4 to 4.6. 
     
     
         10 . The cam piece of  claim 9 , wherein further comprising nickel (Ni), copper (Cu) and molybdenum (Mo), and a total content of nickel (Ni), copper (Cu), and molybdenum (Mo) is 1.9 to 2.1 wt %. 
     
     
         11 . The cam piece of  claim 9 , further comprising 0.3 wt % or less of chromium (Cr). 
     
     
         12 . The cam piece of  claim 9 , further comprising 0.2 to 0.8 wt % of manganese (Mn). 
     
     
         13 . The cam piece of  claim 10 , wherein a content of nickel (Ni) is 1.0 wt % or less. 
     
     
         14 . The cam piece of  claim 10 , wherein a content of copper (Cu) is 0.5 to 1.0 wt %. 
     
     
         15 . The cam piece of  claim 10 , wherein a content of molybdenum (Mo) is 0.5 to 1.0 wt %. 
     
     
         16 . The cam piece of  claim 9 , wherein a spheroidal ratio in the cam piece is 80% or more or a graphite size is in the cam piece 50 μm or less or a shrinkage defect size in the cam piece is 0.1 mm or less. 
     
     
         17 . The cam piece of  claim 10 , wherein a structure of the cam piece is bainite. 
     
     
         18 . The cam piece of  claim 10 , wherein an amount of carbides in the cam piece is 5% or less. 
     
     
         19 . The cam piece of  claim 10 , wherein a tensile strength of the cam piece is 1,200 MPa or more. 
     
     
         20 . The cam piece of  claim 10 , wherein an elongation of the cam piece is 2% or more.