A method for producing a valve body of a hollow valve includes providing a workpiece blank or semi-finished product, spin extruding the workpiece to produce a preform having a cup with a hollow shape formed by the cup wall. A hollow valve produced by this method is also provided.

A poppet valve, in particular a hollow poppet valve, includes: a valve stem; a valve body having along a longitudinal axis, a first end with a neck portion to which the valve stem is coaxially arranged and having along a longitudinal axis a second end with a first conical contact face portion, the valve body including a cavity with a first opening towards the first end and a second opening towards the second end; and a valve cap coaxially arranged to the valve body on the second end for closing the second opening, the valve cap having a second conical contact face portion to form together with the first conical contact face portion a valve head contact face.

A poppet valve, in particular a hollow poppet valve, includes: a valve stem; a valve body having along a longitudinal axis, a first end with a neck portion to which the valve stem is coaxially arranged and having along a longitudinal axis a second end with a first conical contact face portion, the valve body including a cavity with a first opening towards the first end and a second opening towards the second end; and a valve cap coaxially arranged to the valve body on the second end for closing the second opening, the valve cap having a second conical contact face portion to form together with the first conical contact face portion a valve head contact face.

A method of manufacturing an engine valve intermediate product with a boss portion formed in integral fashion at an outer circumferential surface at an intermediate location on a stem forming portion. The manufacturing method may comprise a stem retaining operation in which an intermediate location of the stem forming portion is retained by a plurality of intermediate jigs removably installable radially with respect to a center of the stem forming portion, and a base end portion is retained by a base end jig. The manufacturing method may further comprise a stem enlarging operation in which compressive forces are applied from both ends of the intermediate product and the boss portion is formed as the intermediate product is made to rotate and alternating loads that cause tensile forces and compressive forces to act in repeated and alternating fashion at the outer circumferential surface of the stem forming portion are applied.

A method of manufacturing an engine valve intermediate product with a boss portion formed in integral fashion at an outer circumferential surface at an intermediate location on a stem forming portion. The manufacturing method may comprise a stem retaining operation in which an intermediate location of the stem forming portion is retained by a plurality of intermediate jigs removably installable radially with respect to a center of the stem forming portion, and a base end portion is retained by a base end jig. The manufacturing method may further comprise a stem enlarging operation in which compressive forces are applied from both ends of the intermediate product and the boss portion is formed as the intermediate product is made to rotate and alternating loads that cause tensile forces and compressive forces to act in repeated and alternating fashion at the outer circumferential surface of the stem forming portion are applied.

A poppet valve includes: a valve body comprising a valve stem body, a valve head body with a valve combustion face, and a valve fillet body interconnecting the valve stem body and the valve head body. The valve fillet body surface has an increased thermal resistance compared to the valve combustion face.

A poppet valve includes: a valve body comprising a valve stem body, a valve head body with a valve combustion face, and a valve fillet body interconnecting the valve stem body and the valve head body. The valve fillet body surface has an increased thermal resistance compared to the valve combustion face.

A poppet valve, in particular a hollow poppet valve, includes: a valve stem; a valve body having along a longitudinal axis, a first end with a neck portion to which the valve stem is coaxially arranged and having along a longitudinal axis a second end with a first conical contact face portion, the valve body including a cavity with a first opening towards the first end and a second opening towards the second end; and a valve cap coaxially arranged to the valve body on the second end for closing the second opening, the valve cap having a second conical contact face portion to form together with the first conical contact face portion a valve head contact face.

A poppet valve, in particular a hollow poppet valve, includes: a valve stem; a valve body having along a longitudinal axis, a first end with a neck portion to which the valve stem is coaxially arranged and having along a longitudinal axis a second end with a first conical contact face portion, the valve body including a cavity with a first opening towards the first end and a second opening towards the second end; and a valve cap coaxially arranged to the valve body on the second end for closing the second opening, the valve cap having a second conical contact face portion to form together with the first conical contact face portion a valve head contact face.

A method for producing a valve body of a hollow valve with optimised interior stem geometry includes a preform with a valve plate and a tubular wall surrounding a cavity. Flow forming the tubular wall over a flow-forming mandrel, which is inserted into the cavity to enlarge a length of the tubular wall. An interior area of the tubular wall is embossed with a structure either due to the fact that the flow-forming mandrel is a structuring mandrel having a surface structure, or alternatively, because the method includes a further step of reducing an outer diameter of the tubular wall by swaging or drawing and ironing over a structuring mandrel. Furthermore, a hollow valve is produced by this method.