A method for producing a piston of an internal combustion engine, with a cooling duct, may include producing a piston blank with a cooling duct, closing an inlet and an outlet of the cooling duct by at least one closure element, machine-finishing the piston blank, and removing the at least one closure element.

Methods for forging a piston blank are disclosed such that the forged piston blank is in a near-net shape and size of a final piston. Bending a flange to form a cooling channel can be done with reduced or no preliminary machining away of core material relative prior to bending the flange.

A method for producing a piston for an internal combustion engine may include the steps of: producing a piston upper part from a first blank via a deformation process; producing a piston lower part from a second blank via at least one of a deformation process and a casting process; connecting the first blank of the piston upper part and the second blank of the piston lower part to form a piston body via a welding process; and performing at least one of a secondary machining process and a finish machining process of the piston body to produce the piston.

Methods for forging a piston blank are disclosed such that the forged piston blank is in a near-net shape and size of a final piston. Bending a flange to form a cooling channel can be done with reduced or no preliminary machining away of core material relative prior to bending the flange.

A steel piston with an oil gallery, and process for forming a steel piston oil gallery channel, which corresponds to the complex shape of the combustion bowl in the piston crown. The oil gallery channel is first forged to the basic shape that corresponds to the shape of the walls of the combustion bowl. Machine-turning surfaces in the oil gallery channel can be machine-finished as desired. Surfaces in the oil gallery which cannot be machined with conventional turning operations, such as recesses and protrusions into the channel, are left in the original forged condition.

A piston, particularly a piston for use in a diesel engine, particularly a heavy duty diesel engine, is formed from a billet of metal, such that the finished piston has a mass that is at least 50%, and, more preferably, up to about 62%, of the mass of the billet. Other than finishing steps, the piston is formed with a closed gallery, without loss of mass through machining processes.

A method for producing a cooling duct piston for an internal combustion engine having a cooling duct in its piston crown. A piston main body is produced with a collar which is circumferential and projects radially in the region of the piston crown. The collar is formed until its outer circumferential edge comes very closely or completely into contact with a bearing region of the piston lower part forming the cooling duct. At least one ring groove is introduced. A ring-free groove is further formed below the ring groove, wherein a dividing plane lies between the outer circumferential edge of the formed collar and an upper side of the piston lower part in the ring-free groove.

A piston, particularly a piston for use in a diesel engine, particularly a heavy duty diesel engine, is formed from a billet of metal, such that the finished piston has a mass that is at least 50%, and, more preferably, up to about 62%, of the mass of the billet. Other than finishing steps, the piston is formed with a closed gallery, without loss of mass through machining processes.

The invention relates to a piston of an internal combustion engine including at least one peripheral annular groove. The piston includes an upper part and a lower part permanently joined in the region of a joining plane by a friction welding method. The joining plane may be located between the upper flank and the lower flank of the annular groove. A heat-affected zone is generated due to the use of the friction welding and includes at least one of the upper flank or the lower flank of the annular groove. Where multiple annual grooves are used, the joining plane and heat-affected zone may be positioned on alternate annular grooves.

A method for producing a piston for an internal combustion engine may include the steps of: producing a piston main body from a first blank via a deformation process; producing a piston ring part from a second blank via at least one of a deformation process and a casting process; pre-machining the first blank and the second blank, and finish machining a welding surface of the first blank and a welding surface of the second blank; connecting the pre-machined first blank and the pre-machined second blank via a welding process to form a piston body; and performing at least one of a secondary machining and a finish machining of the piston body to produce the piston.