An automotive internal combustion engine piston is formed to have a bowl in the piston crown, at least one micro chamber formed in a side surface of the piston body at a position lower than a floor of the bowl, and extended orifices to provide 2-way communication of gaseous materials between the micro chambers and bowl. The micro chamber volume is defined by a removable casting core that incorporates a strut to secure the core at the circumference of the piston body in the casting mold. Subsequent to casting and removal of the core material, the cavity from the strut to secure the core is prepared to receive a tapered thread plug that is sealed by circumferential friction stir welding on the outer diameter of the piston body. The micro chamber is thereby isolated except for the extended orifice to the bowl.

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 piston crown is made by a cast metal or powder metal forming process. The oil gallery channel is formed 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 as-formed condition.

A three section steel piston for two-stroke engines is provided. The piston is provided with an upper section, a middle section and a lower section. Piston ring grooves are formed into the upper and lower sections, and pin bosses with openings and skirts are formed into the middle section. The middle section has relatively thinner walls as compared to the portions of the upper and lower sections at the piston ring grooves to reduce the mass of the piston. A closed cooling gallery may be formed adjacent an upper combustion surface of the piston with the cooling gallery being defined at least partially by the upper section.

A method for producing a cooling channel system for an internal combustion engine, which has a cooling channel in the piston crown. The piston crown is adjoined by a lower piston part having a piston boss, pin bores and piston skirts. Firstly, a piston blank having a peripheral collar projecting radially in the region of the piston crown is produced, wherein the collar, forming a subsequent ring zone wall is then reshaped and, in a transition area between the piston crown and the lower piston part, a contact area for the collar is formed, and the collar is reshaped in such a way until the outer radially peripheral edge comes very close to or completely into contact with the contact area in order to form a closed cooling channel. Following the reshaping, the end region of the ring zone wall forms a defined gap (X) with respect to the upper edge of the piston skirt.

A piston for an internal combustion engine is provided. The piston includes a piston body which is made of steel. The piston body has a crown portion with an upper combustion surface, a pair of skirts which depend from the crown surface, a pair of pin bosses for receiving a wrist pin and a plurality of pin boss bridges which extend from the pin bosses to the skirts. Each of the pin boss bridges extends axially to a lower end which is opposite of the crown portion and has a rib with an increased thickness at its lower end. At least one of the pin boss bridges has a generally flat counter-bore surface for providing a reference location for machining of the piston body.

A method and apparatus for simultaneously producing a first piston part and a second piston part via a forging device may include an upper die, at least one intermediate die, and a lower die. A first billet may be placed between the upper die and the intermediate die, and a second billet may be placed between the intermediate die and the lower die. The upper die and the lower die may be configured to be moved toward each other, whereby the first piston part is forged from the first billet and the second piston part is forged at the same time from the second billet. The upper die and the lower die may then be configured to be moved apart, and the piston parts may be removed.

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 piston crown is made by a cast metal or powder metal forming process. The oil gallery channel is formed 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 as-formed condition.

Exemplary piston assemblies and methods of making the same are disclosed. An exemplary piston may include a piston body defining a piston axis, the piston body having a skirt and forming a lower surface of a cooling gallery. The body may include radially inner and outer body mating surfaces. The piston may further include a cooling gallery ring cooperating with the piston body to form the cooling gallery. The piston body and cooling gallery ring may be joined together along radially inner and radially outer interface regions to form a generally one-piece piston assembly. In some exemplary approaches, mating surfaces of the body and ring may be positioned adjacent a support surface configured to inhibit or prevent weld spatter formed in a process joining the ring and body from the cooling gallery.

A piston for an axial machine includes a piston body having a cavity that is closed in a pressure-tight way. The cavity is divided into a plurality of chambers, arranged one beside the other in cross-section.

An exemplary piston may include a piston body having radially inner and outer body mating surfaces. The piston may further include a cooling gallery ring cooperating with the piston body to form a continuous upper combustion bowl surface and a cooling gallery. The cooling gallery ring may have radially inner and outer ring mating surfaces abutted along their corresponding radially inner and outer body mating surfaces, such that the cooling gallery is substantially enclosed. The piston body and cooling gallery ring may be joined together along the radially inner and radially outer interface regions to form a generally one-piece piston assembly. The radially outer interface region may be elongated in a direction parallel to the piston axis, e.g., facilitating a laser welding joining process.