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 method for producing a piston may include aligning at least two piston components along corresponding joining surfaces, activating a laser designed for deep-welding, and aligning a laser beam with a starting point. The method may then include increasing a power density of the laser beam over a first defined path along the joining surfaces to produce a weld seam with an increasing weld seam depth, deep welding along the joining surfaces to produce a deep weld seam with a substantially constant weld seam depth up to a defined end point, and reducing the power density over a second defined path to produce a weld seam with a decreasing weld seam depth. The method may further include overwelding at least part of at least one of the first and second defined paths by a laser designed for heat conduction welding to produce at least one heat conduction weld seam.

A method for producing a piston may include aligning at least two piston components along corresponding joining surfaces, activating a laser designed for deep-welding, and aligning a laser beam with a starting point. The method may then include increasing a power density of the laser beam over a first defined path along the joining surfaces to produce a weld seam with an increasing weld seam depth, deep welding along the joining surfaces to produce a deep weld seam with a substantially constant weld seam depth up to a defined end point, and reducing the power density over a second defined path to produce a weld seam with a decreasing weld seam depth. The method may further include overwelding at least part of at least one of the first and second defined paths by a laser designed for heat conduction welding to produce at least one heat conduction weld seam.

A galleryless piston for an internal combustion engine is provided. The piston has a monolithic piston body including an upper wall forming an upper combustion surface with first and second portions. The first portion extends annularly along an outer periphery of the upper wall and the second portion includes a combustion bowl. The first portion can also include valve pockets formed therein to reduce weight. The upper wall has an undercrown surface directly opposite the second portion of the upper combustion surface. To enhance cooling, a center portion of the undercrown surface is concave, such that oil is channeled during reciprocation of the piston from one side to the opposite side of the piston. The concave center portion is axially offset from the surrounding area of the undercrown surface.

A galleryless piston for an internal combustion engine is provided. The piston has a monolithic piston body including an upper wall forming an upper combustion surface with first and second portions. The first portion extends annularly along an outer periphery of the upper wall and the second portion includes a combustion bowl. The first portion can also include valve pockets formed therein to reduce weight. The upper wall has an undercrown surface directly opposite the second portion of the upper combustion surface. To enhance cooling, a center portion of the undercrown surface is concave, such that oil is channeled during reciprocation of the piston from one side to the opposite side of the piston. The concave center portion is axially offset from the surrounding area of the undercrown surface.

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 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.

This piston includes a piston main body made of aluminum or an aluminum alloy, used in an internal combustion and a modified layer formed on a surface of a strength reinforced portion of the piston main body, having a surface made of aluminum oxide by plasma oxidation, to which compressive residual stress is applied.

A galleryless piston for an internal combustion engine is provided. The piston has a monolithic piston body including an upper wall forming an upper combustion surface with first and second portions. The first portion extends annularly along an outer periphery of the upper wall and the second portion includes a combustion bowl. The first portion can also include valve pockets formed therein to reduce weight. The upper wall has an undercrown surface directly opposite the second portion of the upper combustion surface. To enhance cooling, a center portion of the undercrown surface is concave, such that oil is channeled during reciprocation of the piston from one side to the opposite side of the piston.

A galleryless piston for an internal combustion engine is provided. The piston has a monolithic piston body including an upper wall forming an upper combustion surface with first and second portions. The first portion extends annularly along an outer periphery of the upper wall and the second portion includes a combustion bowl. The first portion can also include valve pockets formed therein to reduce weight. The upper wall has an undercrown surface directly opposite the second portion of the upper combustion surface. To enhance cooling, a center portion of the undercrown surface is concave, such that oil is channeled during reciprocation of the piston from one side to the opposite side of the piston.