Method and apparatus for forging gear

Abstract

A method for forging a gear according to the present disclosure includes pushing a material into a molding space of a teeth profile die from one side of the teeth profile die for molding external teeth by a punch, and after the pushing, discharging a gear having the external teeth formed thereon from another side of the teeth profile die by the punch. The method further includes providing a material outer diameter constraint die for constraining an outer diameter of a previous material before the material is pushed into the molding space of the teeth profile die on the one side of the teeth profile die, and setting an inner diameter size of the material outer diameter constraint die to be smaller than a large diameter size of the gear set in the teeth profile die.

What is claimed is: 
     
         1 . A method for forging a gear including pushing a material into a molding space of a teeth profile die from one side of the teeth profile die for molding external teeth by a punch, and after the pushing, discharging a gear having the external teeth formed thereon from another side of the teeth profile die by the punch, the method comprising:
 providing a material outer diameter constraint die for constraining an outer diameter of a previous material before the material is pushed into the molding space of the teeth profile die on the one side of the teeth profile die; and   setting an inner diameter size of the material outer diameter constraint die to be smaller than a large diameter size of the gear set in the teeth profile die.   
     
     
         2 . The method for forging a gear according to  claim 1 , wherein the inner diameter size of the material outer diameter constraint die is set to be greater than a pitch circle diameter size of the gear set in the teeth profile die. 
     
     
         3 . The method for forging a gear according to  claim 1 , wherein a teeth profile shape of the teeth profile die is carved on an inner peripheral surface of the material outer diameter constraint die at an outer side in a radial direction than the inner diameter size of the material outer diameter constraint die. 
     
     
         4 . An apparatus for forging a gear comprising:
 a teeth profile die for molding external teeth;   a material outer diameter constraint die provided on one side of the teeth profile die and configured to constrain an outer diameter of a material; and   a punch configured to push the material, the outer diameter of which has been constrained by the material outer diameter constraint die, into a molding space of the teeth profile die from the one side of the teeth profile die, and then discharge a gear having the external teeth formed thereon from another side of the teeth profile die,   wherein an inner diameter size of the material outer diameter constraint die is set to be smaller than a large diameter size of a teeth profile of the gear set in the teeth profile die.   
     
     
         5 . The apparatus for forging a gear according to  claim 4 , wherein the inner diameter size of the material outer diameter constraint die is set to be greater than a pitch circle diameter size of the gear set in the teeth profile die. 
     
     
         6 . The apparatus for forging a gear according to  claim 4 , wherein a teeth profile shape of the teeth profile die is carved on an inner peripheral surface of the material outer diameter constraint die at an outer side in a radial direction than the inner diameter size of the material outer diameter constraint die.