Patent ID: 7059052

Claim:
A method of producing a hydrodynamic type porous oil-impregnated bearing comprising a porous bearing body being formed with bearing surface on an inner peripheral surface thereof, said bearing surface having inclined hydrodynamic pressure generating grooves, and oil retained in pores of said bearing body by impregnation of lubricating oil or lubricating grease, said method comprising the steps of: inserting a forming pattern in an inner peripheral surface of a cylindrical porous blank, said forming pattern having a first forming portion for forming a region of said hydrodynamic pressure generating grooves and a second forming portion for forming the other region in said bearing surface, press fitting said porous blank with said forming pattern inserted therein into a die to apply a compacting pressure to said porous blank wherein the inner peripheral surface of said porous blank is pressed against said forming pattern, thereby simultaneously forming the region of said hydrodynamic pressure generating grooves and the other region in said bearing surface on the inner peripheral surface of said porous blank, and after forming said bearing surface, 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.