Cam lobe material, camshaft using the same and method for producing cam lobe member

Abstract

The present invention provides a cam lobe material that is excellent in sliding characteristics, such as wear resistance, scuffing resistance and pitting resistance, and can be advantageously used in engines to which high loads are applied, and a method of manufacturing the cam lobe material. The above-described task is fulfilled by providing a cam lobe material that is formed from an iron-based sintered alloy that contains 0.3 to 5.0 mass % Ni, 0.5 to 1.2 mass % C, 0.02 to 0.3 mass % of at least either of B and P, and incidental impurities as the balance, and has a hardness of a peripheral surface of not less than HRC 50 and a density of not less than 7.5 g/cm 3 . The iron-based sintered alloy can further contain not more than 2.5 mass % Mo. The above-described task can also be fulfilled by a method of manufacturing the cam lobe material, that a compression molding step and a sintering step are repeated at least twice, the compression molding step involving compression molding iron-based alloy powders prepared so as to provide the composition of the ferrous sintered alloy in a prescribed cam lobe shape, and the sintering step involving sintering the compression molded compact body, and that the sintered body is subjected to quench and tempering treatment.

1 . A cam lobe material, characterized in that the cam lobe material is formed from an iron-based sintered alloy that contains 0.3 to 5.0 mass % Ni, 0.5 to 1.2 mass % C, 0.02 to 0.3 mass % of at least either of B and P, and incidental impurities as the balance, and has a hardness of a peripheral surface of not less than HRC 50 and a density of not less than 7.5 g/cm 3 .  
   
   
       2 . The cam lobe material according to  claim 1 , characterized in that the iron-based sintered alloy further contains not more than 2.5 mass % Mo.  
   
   
       3 . The cam lobe material according to  claim 1 , characterized in that the cam lobe material uses a roller follower as a mating member.  
   
   
       4 . A cam shaft, characterized in that the cam shaft is provided with a cam lobe formed from the cam lobe material according to  claim 1 .  
   
   
       5 . A method of manufacturing the cam lobe material according to  claim 1 , characterized in that a compression molding step and a sintering step are repeated at least twice, the compression molding step involving compression molding iron-based alloy powders prepared so as to provide the composition of the ferrous sintered alloy in a prescribed cam lobe shape, and the sintering step involving sintering the compression molded compact body, and that the sintered body is subjected to quench and tempering treatment.  
   
   
       6 . The method of manufacturing the cam lobe material according to  claim 5 , characterized in that the peripheral surface of the cam lobe material is shot blasted.