Apparatus and method for forming product having asymmetric cross-section using ring rolling process

A method of forming a ring product from a blank using a ring rolling apparatus, the method comprising:

• providing a blank, said blank having a ring shape with an annular inner wall surface, an annular outer wall surface, an upper surface, and a lower surface;
• forming a depressed portion in the annular inner wall surface of the blank;
• providing a ring rolling apparatus, said ring rolling apparatus including a main roll for pressing the annular outer wall surface of the blank, a pressure roll for pressing the annular inner wall surface of the blank, the pressure roll having an cylindrical shape with a protrusion with enlarged diameter, and a plurality of axial rolls for pressing the upper and lower surfaces of the blank;
• pressing the annular inner wall surface of the blank using the pressure roll and with the protrusion of the pressure roll axially aligned to be in contact with the depressed portion the annular inner wall surface of the blank;
• and
• axially displacing the pressure roll to move the protrusion of the pressure roll in the axial direction of the ring shaped blank, said axially displacing the pressure roll being performed during the process of performing said pressing the annular inner wall surface of the blank,
• wherein an axial displacement (X) of the pressure roll is obtained from the equation of:
• X
• =
• H
• +
• dT
• ⁢
• ⁢
• 1
• ⁢
• (
• w
• ⁢
• ⁢
• 1
• w
• ⁢
• ⁢
• 2
• ·
• d
• ⁢
• ⁢
• 1
• +
• 2
• ⁢
• ⁢
• R
• +
• w
• ⁢
• ⁢
• 1
• d
• ⁢
• ⁢
• 2
• +
• 2
• ⁢
• ⁢
• R
• +
• w
• ⁢
• ⁢
• 2
• -
• 1
• )
• where H denotes a height difference between the blank and a final product, dT1 denotes a height of the depressed portion of the blank, w1 denotes a width of the blank except for the depressed portion, w2 denotes a width of the final product except for the depressed portion, d1 denotes an inner diameter of the blank, d2 denotes an inner diameter of the final product, and R denotes a width of the depressed portion.