US 11,732,622 B2
Method for producing a hollow valve with an optimised interior stem geometry for internal combustion engines
Thorsten Matthais, Garbsen (DE); Antonius Wolking, Barsinghausen (DE); and Guido Bayard, Dortmund (DE)
Assigned to Federal-Mogul Valvetrain GmbH, Barsinghausen (DE)
Appl. No. 17/57,469
Filed by FEDERAL-MOGUL VALVETRAIN GMBH, Barsinghausen (DE)
PCT Filed Apr. 18, 2019, PCT No. PCT/EP2019/060103
§ 371(c)(1), (2) Date Nov. 20, 2020,
PCT Pub. No. WO2019/223941, PCT Pub. Date Nov. 28, 2019.
Claims priority of application No. 10 2018 112 295.0 (DE), filed on May 23, 2018.
Prior Publication US 2021/0199029 A1, Jul. 1, 2021
Int. Cl. F01L 3/14 (2006.01); B21D 22/16 (2006.01); B21K 1/22 (2006.01)
CPC F01L 3/14 (2013.01) [B21D 22/16 (2013.01); B21K 1/22 (2013.01); F01L 2301/00 (2020.05)] 15 Claims
OG exemplary drawing
 
1. A method for producing a valve body of a hollow valve with optimized interior stem geometry, comprising the steps of:
providing a preform with a valve head and a tubular wall surrounding a cylindrical cavity;
flow forming the tubular wall over a mandrel, which is inserted into the cavity, to enlarge a length of the tubular wall,
wherein multiple forming rollers are used in the flow forming process;
wherein the mandrel is provided with a non-cylindrical outer surface structure, and wherein the multiple forming rollers are offset radially and axially to each other during the flow forming process.