Method and Device for Forging Bevel Gear

Abstract

A method and a device for forging a bevel gear. The device includes a punch, a work positioning and holding die positioning and holding a work placed on the placing surface of a lower die, and an outer burr removing die removing outer burrs produced on the outer peripheral surfaces of the teeth of the work. In the state of the work positioned and held at a prescribed position by the work positioning and holding die, the inner burrs and the outer burrs of the work are simultaneously removed by the integrated lowering operation of the punch and the outer burr removing die.

1 . An apparatus for forging a bevel gear, comprising:
 a lower die having a mount surface for mounting a workpiece thereon, said lower die being mounted on a base for rotation in a circumferential direction;   a punch mounted for vertical movement with respect to said lower die, for piercing a central portion of said workpiece in order to remove an inner burr thereof;   a workpiece positioning and holding die fitted over said punch for displacement in unison with the punch, for pressing the workpiece that is mounted on said mount surface of said lower die against said lower die, for thereby positioning and holding the workpiece; and   an outer deburring die fitted over said workpiece positioning and holding die and displaceable in unison with said punch, for removing outer burrs produced between teeth of said workpiece along an outer circumference of said workpiece,   wherein while said workpiece is positioned in a predetermined position and held in said position by said workpiece positioning and holding die, the inner burr and the outer burrs of said workpiece are simultaneously removed by movement of said punch and said outer deburring die in unison with each other.   
   
   
       2 . The apparatus according to  claim 1 , further comprising a spring member by which said lower die is floatingly supported on said base. 
   
   
       3 . The apparatus according to  claim 1 , wherein said workpiece positioning and holding die comprises engaging fingers for positioning said workpiece in circumferential directions thereof, by entering along and engaging within valleys located between the teeth of said workpiece, and a pressing holder that abuts against an upper surface of said workpiece and presses said workpiece against the lower die to thereby hold said workpiece. 
   
   
       4 . The apparatus according to  claim 1 , wherein said lower die includes an annular flange having an end face that is engaged by an end of said spring member, and which is slidably displaceable vertically along an annular boss of said base. 
   
   
       5 . An apparatus for forging a bevel gear, comprising:
 a lower die having a mount surface for mounting a workpiece thereon, said lower die being mounted on a base for rotation in a circumferential direction;   a punch mounted for vertical movement with respect to said lower die, for piercing a central portion of said workpiece in order to remove an inner burr thereof;   a workpiece pressing die fitted over said punch for displacement in unison with said punch, for pressing the workpiece that is mounted on said mount surface of said lower die against said lower die, for thereby holding the workpiece; and   a positioning and deburring die fitted over said workpiece pressing die and displaceable in unison with said punch, for correcting circumferential positional errors of said workpiece and positioning said workpiece, and for removing outer burrs produced between teeth of said workpiece along an outer circumference of said workpiece,   wherein while said workpiece positioned in a predetermined position is held in said position by said workpiece pressing die, the inner burr and the outer burrs of said workpiece are simultaneously removed by movement of said punch and said positioning and deburring die in unison with each other.   
   
   
       6 . The apparatus according to  claim 5 , further comprising a spring member by which said lower die is floatingly supported on said base. 
   
   
       7 . The apparatus according to  claim 5 , wherein said positioning and deburring die comprises engaging protrusions for positioning said workpiece in circumferential directions thereof by entering along and engaging within valleys located between the teeth of said workpiece, and cutting edges for removing the outer burrs produced between the teeth of said workpiece along the outer circumference of said workpiece. 
   
   
       8 . The apparatus according to  claim 7 , wherein said engaging protrusions project vertically downward a predetermined distance from a lower end face of said workpiece pressing die. 
   
   
       9 . A method of forging a bevel gear, comprising the steps of:
 forging a forging stock in a single forging cycle or in a plurality of forging cycles, to thereby produce an intermediate form having teeth;   placing said intermediate form on a mount surface of a lower die, and positioning and holding said intermediate form in a predetermining position with a positioning and holding die, which is fitted over a punch, for displacement in unison with said punch; and   while said intermediate form is positioned and held by said positioning and holding die, simultaneously piercing said intermediate form in order to remove an inner burr thereof with said punch, and removing outer burrs of said intermediate form with an outer deburring die, which is fitted over said positioning and holding die, for displacement in unison with said punch.   
   
   
       10 . The method according to  claim 9 , wherein said intermediate form is positioned when engaging fingers disposed on an end of said positioning and holding die engage within valleys located between the teeth of said intermediate form. 
   
   
       11 . A method of forging a bevel gear, comprising the steps of:
 forging a forging stock in a single forging cycle or in a plurality of forging cycles, to thereby produce an intermediate form having teeth;   placing said intermediate form on a mount surface of a lower die, correcting circumferential positional errors of said intermediate form, and positioning said intermediate form with a positioning and deburring die, which is fitted over a punch, for displacement in unison with the punch, and thereafter, positioning and holding said intermediate form in a predetermined position with a workpiece pressing die that is fitted in said positioning and deburring die; and   while said intermediate form is positioned and held by said workpiece pressing die, simultaneously piercing said intermediate form in order to remove an inner burr thereof with said punch, and removing outer burrs of said intermediate form with said positioning and deburring die, which is displaced in unison with the punch.   
   
   
       12 . The method according to  claim 11 , wherein said intermediate form is positioned when engaging protrusions disposed on said positioning and deburring die engage within valleys located between the teeth of said intermediate form.