Hydrodynamic type porous oil-impregnated bearing

A method of producing a porous bearing body of a hydrodynamic type porous oil-impregnated bearing, said porous bearing body being formed with bearing surface on an inner peripheral surface thereof, said bearing surface having a plurality of inclined hydrodynamic pressure generating grooves, said method comprising the steps of:

• inserting a forming pattern in an inner peripheral surface of a cylindrical porous blank, said porous blank being made of a sintered metal, said forming pattern having a forming portion for forming said hydrodynamic pressure generating grooves, said forming portion being composed of a plurality of convex portions each of which agrees with each of said hydrodynamic press generating grooves,
• press fitting said porous blank with said forming pattern inserted therein into a die to supply a compacting pressure to said porous blank wherein the inner peripheral surface of said porous blank is pressed against said forming portion of said forming pattern, thereby forming said hydrodynamic pressure generating grooves in the inner peripheral surface of said porous blank, and
• after forming said hydrodynamic pressure generating grooves, removing said compacting pressure so as to utilize the spring-back of said porous blank in releasing said forming pattern from the inner peripheral surface of said porous blank.

A method of producing a hydrodynamic porous oil-impregnated bearing, a porous bearing body of which is formed with bearing surface on an inner peripheral surface thereof, said bearing surface having inclined hydrodynamic pressure generating grooves, said method comprising the steps of:

• inserting a forming pattern in an inner peripheral surface of a porous blank, said forming pattern having a forming portion for forming said hydrodynamic pressure generating grooves, said forming portion comprising a plurality of convex portions, each of which agrees with each of said hydrodynamic pressure generating grooves,
• press fitting said porous blank with said forming pattern inserted therein into a die to apply a compacting pressure to said porous blank wherein said inner peripheral surface of said porous blank is pressed against said forming pattern, thereby making plastic deformation of said inner peripheral surface of said porous blank occur to form said hydrodynamic pressure generating grooves, and
• after forming said hydrodynamic pressure generating grooves, removing said compacting pressure so as to utilize the spring-back of said porous blank in releasing said forming pattern from the inner peripheral surface of said porous blank.