A method for manufacturing an engine poppet valve having a valve head portion and a stem portion made integral by way of a neck portion that increases in diameter toward a tip end, comprising: a valve head portion manufacturing operation in which hot forging is employed to form a stem/head intermediate product comprising an intermediate stem portion and a valve head portion which is made integral with the intermediate stem portion by way of a neck portion; a stepped stem portion manufacturing operation in which cold drawing in which a part of the intermediate stem portion is inserted in press-fit fashion from a base end portion into a stem member inlet surface and a stem member compressing surface of a hollow circular hole die that has a drawing hole and at which the stem member inlet surface that gradually narrows toward a central axis, and the stem member compressing surface that is continuous with the stem member inlet surface and that has a constant inside diameter which is less than an outside diameter of the intermediate stem portion are provided at least at a portion thereof is employed to cause a stepped stem portion comprising a first stem portion which has been made to be of decreased diameter, a step portion which has been formed by the stem member inlet surface, and a second stem portion in which there is absence of decrease in diameter and which is continuous by way of the step portion with the first stem portion to be formed from the intermediate stem portion; and a joining operation in which a stem end portion having a same outside diameter as the first stem portion is joined to a base end portion of the first stem portion.

At a diameter-decreasing operation during manufacture of a poppet valve, an intermediate stem portion at which a valve head portion and an intermediate stem portion are made integral by way of a neck portion may be inserted between/among diameter-decreasing tools. Application of compressive forces from compressing surfaces of the diameter-decreasing tools may cause a part of the intermediate stem portion to be decreased in diameter and may cause a main body portion of a first stem portion to be formed and may cause formation of a stepped portion which is continuous with the main body portion, and formation, by an absence of decrease in diameter, of a second stem portion which is broader in girth than the main body portion and which is continuous with the neck portion and which is also continuous with the main body portion by way of the stepped portion.

A method for shaping a hollow valve preform of a pull rod (20) includes a structuring bulb (22) which is inserted into the cavity (56) of a shaft portion (44) of a valve preform. The structuring bulb (22) has an outer diameter, and has an outer structuring, whereafter the hollow shaft portion (44) is shaped, wherein at least a portion of an inner diameter of the cavity (56) is reduced below an outer diameter of the structuring bulb (22). The structuring bulb (22) is then pulled out through the shaped shaft portion (44), wherein the outer structuring is at least partially pressed into the surface of the cavity (56).

A method for shaping a hollow valve preform of a pull rod (20) includes a structuring bulb (22) which is inserted into the cavity (56) of a shaft portion (44) of a valve preform. The structuring bulb (22) has an outer diameter, and has an outer structuring, whereafter the hollow shaft portion (44) is shaped, wherein at least a portion of an inner diameter of the cavity (56) is reduced below an outer diameter of the structuring bulb (22). The structuring bulb (22) is then pulled out through the shaped shaft portion (44), wherein the outer structuring is at least partially pressed into the surface of the cavity (56).

The present invention for coating a valve head (6) of an inlet and/or outlet valve (4) comprises a preparation of a surface, which is to be coated, of the valve (4) for a coating, and a coating of the prepared surface with a ceramic high-temperature coating (22).

The present invention for coating a valve head (6) of an inlet and/or outlet valve (4) comprises a preparation of a surface, which is to be coated, of the valve (4) for a coating, and a coating of the prepared surface with a ceramic high-temperature coating (22).

A method for producing at least one hollow valve for gas exchange may include introducing a bore into a valve shaft and into a valve head to form the at least one hollow valve, measuring a depth of the bore, washing the at least one hollow valve at least once, providing the at least one hollow valve in a retaining device, orienting the retaining device together with the at least one hollow valve with respect to an associated electrode, moving the associated electrode in relation to the at least one hollow valve, inserting the associated electrode into the bore of the at least one hollow valve, enlarging the bore in a region of the valve head by electromechanical machining processes, removing the associated electrode from the at least one hollow valve, rinsing and/or preserving the at least one hollow valve, and measuring a wall thickness of a valve bottom.

A device for producing at least one hollow valve for a gas exchange system may include at least one valve holder. The at least one valve holder may include a valve stem centring element, a valve receptacle and a valve head holder. The valve receptacle may receive a valve stem and the valve head holder may receive a valve head. A first carrier and a second carrier may be provided. The valve holder may be arranged on the first carrier. At least one cathode holder may be arranged on the second carrier. The cathode holder may include a cathode that is insertable through the first carrier via the valve stem centring element. At least one contact plate may be arranged opposite the valve head holder.

A device for producing at least one hollow valve for a gas exchange system may include at least one valve holder. The at least one valve holder may include a valve stem centring element, a valve receptacle and a valve head holder. The valve receptacle may receive a valve stem and the valve head holder may receive a valve head. A first carrier and a second carrier may be provided. The valve holder may be arranged on the first carrier. At least one cathode holder may be arranged on the second carrier. The cathode holder may include a cathode that is insertable through the first carrier via the valve stem centring element. At least one contact plate may be arranged opposite the valve head holder.

An engine valve having a shaft portion and a head portion expanding in diameter like a head at an edge of the shaft portion, and being to open and close a port provided in a cylinder head, wherein the head portion has a head front surface on a bottom side facing a combustion chamber side, a head rear surface on a top side facing the port side, and an outer peripheral surface of the head portion formed between the head front surface and the head rear surface, and the head portion is provided a mirror-finished mirror portion, and the head portion is provided a mirror-finished mirror portion on the entire area of the head front surface exposed to the combustion chamber and the entire area of the outer peripheral surface exposed to the combustion chamber.