Forging apparatus and method

Abstract

The present disclosure provides a method of upset forging comprising inserting a stock material into a die, the stock material having a free axial portion with upper and lower surfaces. Next, a punch is used to apply an axial (e.g. horizontal) compression force against the free axial portion of the stock material whilst constraining the upper and lower surfaces of the free axial portion. The constraining position restricts movement of the free axial portion in a direction substantially perpendicular (e.g. vertical) to the axial compression force thus preventing buckling of the free axial portion.

We claim: 
     
         1 . A method of upset forging comprising inserting stock material into a die, such that the stock material has a holding portion and a free axial portion with upper and lower surfaces, the holding portion held in a holding section of the die preventing movement of the stock material in the holding section both in a parallel and perpendicular direction relative to the axial compression force, and using a punch to apply an axial compression force against the free axial portion whilst constraining the upper and lower surfaces of the free axial portion during forging of the free axial portion so as to restrict movement of the free axial portion in a direction substantially perpendicular to the axial compression force. 
     
     
         2 . A method according to  claim 1 , wherein an axial length of the free axial portion is greater than 3 times (optionally 4 or 4.5 times) a thickness of the free axial portion. 
     
     
         3 . A method according to  claim 1  for forming a fan blade for a gas turbine engine, the method comprising applying an axial compression force to compress the free axial portion of the stock material to form a root section having an increased cross-sectional area. 
     
     
         4 . A method according to  claim 1  comprising inserting the stock material into the die such that the free axial portion is positioned within a constraining section of the die and preventing movement of the free axial portion of the stock material in a perpendicular direction relative to the axial compression force during forging of the free axial portion whilst allowing axial compression of the free axial portion. 
     
     
         5 . A method according to  claim 1  comprising inserting the stock material between a first plate and a second plate of a split die where the first and second plates are spaced by a first distance in the holding section, the first spacing equaling the thickness of the portion of the stock material. 
     
     
         6 . A method according to  claim 5  comprising inserting the free axial portion of the stock material in the constraining section where the first plate and second plate are spaced by a third spacing, the third spacing being up to 5% greater than the first spacing. 
     
     
         7 . A method according to  claim 1  comprising preventing vertical movement of the free axial portion of stock material by vertically constraining the upper and lower surfaces of the free axial portion during forging of the free axial portion upon application of a horizontal compression force. 
     
     
         8 . A die for upset forging by axial compression of a stock material having a holding portion and a free axial portion with upper and lower surfaces, said die having a holding section at a first axial end for securing the holding portion and a constraining section at a second axial end, the holding section and constraining section being axially spaced by a cavity, the constraining section for constraining the upper and lower surfaces of the free axial portion so as to restrict movement of the free axial portion in a direction substantially perpendicular to the axial compression. 
     
     
         9 . A die according to  claim 8  wherein the holding section is adapted to prevent movement of the stock material both in a parallel and perpendicular direction relative to the axial compression. 
     
     
         10 . A die according to  claim 8  comprising a first plate and a second plate spaced by a first distance in the holding section, a second spacing in the cavity and a third spacing in the constraining section, wherein the first and second plates in the constraining section define an opening at the second axial end for receiving a punch and the constraining section extends from the cavity to the opening. 
     
     
         11 . A die according to  claim 10  wherein the second spacing is greater than the first and third spacing. 
     
     
         12 . A die according to  claim 10  wherein the third spacing is up to 5% greater than the first spacing. 
     
     
         13 . A die according to  claim 12  wherein the first and third spacings are approximately equal. 
     
     
         14 . A die according to  claim 10  wherein the die has a diverging section distal the opening in which the first and second plates diverge from the first spacing of the holding section to the increased second spacing of the cavity. 
     
     
         15 . A die according to  claim 14  further comprising a converging section proximal the opening in which the first and second plates converge to form the constraining section. 
     
     
         16 . A die according to  claim 10  wherein the first plate is substantially planar and the diverging section is formed by the second plate diverging from the first plate, the second plate creating an inner end wall defining the cavity distal the opening. 
     
     
         17 . A die according to  claim 16  wherein the converging section of the die is formed by the second plate converging towards the first plate, the second plate creating a second inner end wall defining the cavity proximal the opening. 
     
     
         18 . A die according to  claim 8  wherein the die is horizontally arranged and the holding section is adapted to prevent horizontal and vertical movement of the portion of stock material and the constraining section is adapted to prevent vertical movement of the free axial end. 
     
     
         19 . A forging apparatus comprising a die according to  claim 8 , and a punch for applying an axial force against the free axial portion of the stock material.