Production method for sintered part

Abstract

A production method for a sintered part comprises preparing a metal powder and a binder composed of a thermoplastic resin and a wax, mixing the metal powder and 40 to 60 vol. % of the binder with respect to the metal powder into a mixed powder, and heating and kneading the mixed powder into a raw material. This production method further includes supplying a predetermined amount of the raw material in a hole of a die and compacting the raw material into a green compact having a predetermined shape by pressing the raw material by a punch. This production method further includes ejecting the green compact from the hole of the die, removing the binder from the ejected green compact by heating, and sintering the green compact by heating so as to diffusion bond particles of the green compact. The compacting is performed by pressing at a moving rate U of the punch, which is not more than a rate calculated from the following equation (1). In this case, ΔP (Pa) is pressing power of the punch, μ (Pa·s) is viscosity of the raw material, L (m) is a length of the green compact, and De (m) is a corresponding tube diameter. U=ΔP /(32μ× L )× De 2   (1)

1 . A production method for a sintered part, comprising:
 preparing a metal powder and a binder composed of a thermoplastic resin and a wax;   mixing the metal powder and 40 to 60 vol. % of the binder with respect to the metal powder into a mixed powder;   heating and kneading the mixed powder into a raw material;   supplying a predetermined amount of the raw material in a hole of a die;   compacting the raw material into a green compact having a predetermined shape by pressing the raw material by a punch;   ejecting the green compact from the hole of the die;   removing the binder from the ejected green compact by heating; and   sintering the green compact by heating so as to diffusion bond particles of the green compact,   wherein the compacting is performed by pressing at a moving rate U of the punch, which is not more than a rate calculated from the following equation (1):
     U=ΔP /(32μ× L )× De   2    (1) 
   
     based on ΔP (Pa) as pressing power of the punch, μ (Pa·s) as viscosity of the raw material, L (m) as a length of the green compact, and De (m) as a corresponding tube diameter. 
   
   
       2 . A production method for a sintered part, comprising:
 preparing a metal powder and a binder composed of a thermoplastic resin and a wax;   mixing the metal powder and 40 to 60 vol. % of the binder with respect to the metal powder into a mixed powder;   heating and kneading the mixed powder into a raw material;   supplying a predetermined amount of the raw material in a hole of a die;   compacting the raw material into a green compact having a predetermined shape by pressing the raw material by a punch;   ejecting the green compact from the hole of the die;   removing the binder from the ejected green compact by heating; and   sintering the green compact by heating so as to diffusion bond particles of the green compact;   wherein the die is made of a magnetic die material, the die has a forming surface at the hole, and the die is provided with a cooling device for running a cooling medium at the inside along the forming surface and is provided with a high-frequency induction heating device around the cooling device,   wherein the raw material supplied in the hole of the die is heated by heating the hole by the heating device,   wherein the punch is drive controlled by a servo device in the compacting, and   wherein the green compact is cooled by cooling the hole of the die by the cooling device after the compacting, and then the ejecting is performed.   
   
   
       3 . A production method for a sintered part, comprising:
 preparing a metal powder and a binder composed of a thermoplastic resin and a wax;   mixing the metal powder and 40 to 60 vol. % of the binder with respect to the metal powder into a mixed powder;   heating and kneading the mixed powder into a raw material;   supplying a predetermined amount of the raw material in a hole of a die;   compacting the raw material into a green compact having a predetermined shape by pressing the raw material by a punch;   ejecting the green compact from the hole of the die;   removing the binder from the ejected green compact by heating; and   sintering the green compact by heating so as to diffusion bond particles of the green compact,   wherein the die is made of a magnetic die material, the die has a forming surface at the hole, and the die is provided with a cooling device for running a cooling medium at the inside along the forming surface and is provided with a high-frequency induction heating device around the cooling device,   wherein the raw material supplied in the hole of the die is heated by heating the hole by the heating device,   wherein the punch is drive controlled by a servo device in the compacting, and the compacting is performed by pressing at a moving rate U of the punch, which is not more than a rate calculated from the following equation (1):
     U=ΔP /(32μ× L )× De   2    (1) 
   
     based on ΔP (Pa) as pressing power of the punch, μ (Pa·s) as viscosity of the raw material, L (m) as a length of the green compact, and De (m) as a corresponding tube diameter, and
 wherein the green compact is cooled by cooling the hole of the die by the cooling device after the compacting, and then the ejecting is performed. 
 
   
   
       4 . The production method for the sintered part according to  claim 1 , wherein the compacting is performed at a moving rate U of the punch, which is not less than 80% of a rate calculated from the equation (1). 
   
   
       5 . The production method for the sintered part according to  claim 3 , wherein the compacting is performed at a moving rate U of the punch, which is not less than 80% of a rate calculated from the equation (1).