US 11,898,473 B2
Method and device for manufacturing hollow, internally cooled valves
Thorsten Matthias, Garbsen (DE); and Dirk Schober, Uetze (DE)
Assigned to Federal-Mogul Valvetrain GmbH, Barsinghausen (DE)
Appl. No. 17/772,214
Filed by FEDERAL-MOGUL VALVETRAIN GMBH, Barsinghausen (DE)
PCT Filed Jul. 22, 2020, PCT No. PCT/EP2020/070669
§ 371(c)(1), (2) Date Apr. 27, 2022,
PCT Pub. No. WO2021/104688, PCT Pub. Date Jun. 3, 2021.
Claims priority of application No. 102019132085.2 (DE), filed on Nov. 27, 2019.
Prior Publication US 2022/0403761 A1, Dec. 22, 2022
Int. Cl. B21J 5/12 (2006.01); B21K 1/22 (2006.01); B23P 15/00 (2006.01); F01L 3/14 (2006.01)
CPC F01L 3/14 (2013.01) [B21J 5/12 (2013.01); B21K 1/22 (2013.01); B23P 15/002 (2013.01); F01L 2303/01 (2020.05)] 12 Claims
OG exemplary drawing
 
1. A method for shaping a hollow valve preform comprising:
providing a valve preform, which comprises a head portion and a hollow shaft portion comprising a cavity, wherein the shaft portion has an initial outer diameter and an initial inner diameter,
providing a pull rod having an enlarged structuring bulb at an insertion end of the pull rod that is smaller in outer diameter than the initial inner diameter of the hollow shaft portion of the valve preform,
inserting the pull rod and structuring bulb into the cavity, wherein the structuring bulb has an outer structuring,
shaping the hollow shaft portion, wherein at least a portion of an inner diameter of the shaft portion is reduced to be less than the outer diameter of the structuring bulb, and
therefore pulling out the structuring bulb through the shaped shaft portion, wherein the outer structuring of the structuring bulb is at least partially pressed into the reduced inner diameter surface of the shaft portion to shape the inner diameter surface.