A piston ring includes an annular main body 2 having a side surface 2a and a side surface 2b, and an inner peripheral surface 2c and an outer peripheral surface 2d, wherein in the main body 2, a cutout section 21 is provided in a corner section 31 formed by the side surface 2b and the outer peripheral surface 2d. The cutout section 21 has a first surface 21a and a second surface 21b. An angle 1 formed by the first surface 21a and the side surface 2b is an obtuse angle, and a corner section 32 formed by the second surface 21b and the outer peripheral surface 2d is located between the side surface 2b and the side surface 2a in a width direction of the main body 2.

A piston ring includes an annular main body 2 having a side surface 2a and a side surface 2b, and an inner peripheral surface 2c and an outer peripheral surface 2d, wherein in the main body 2, a cutout section 21 is provided in a corner section 31 formed by the side surface 2b and the outer peripheral surface 2d. The cutout section 21 has a first surface 21a and a second surface 21b. An angle 1 formed by the first surface 21a and the side surface 2b is an obtuse angle, and a corner section 32 formed by the second surface 21b and the outer peripheral surface 2d is located between the side surface 2b and the side surface 2a in a width direction of the main body 2.

The invention relates to a stamp-sealing unit comprising a punch designed as a sonotrode (8), and a die (5), said die (5) having an opening (15) and the punch being able to be moved in and out of the opening (15) in the stamping direction. The invention also relates to an ultrasonic processing device for stamping stamped parts out of a stamping material (2) and for sealing the stamped parts to unprocessed products (21).

The invention relates to a stamp-sealing unit comprising a punch designed as a sonotrode (8), and a die (5), said die (5) having an opening (15) and the punch being able to be moved in and out of the opening (15) in the stamping direction. The invention also relates to an ultrasonic processing device for stamping stamped parts out of a stamping material (2) and for sealing the stamped parts to unprocessed products (21).

Provided is a piston ring (10) comprising a sliding surface (11) covered with a CrBVN alloy film (3), wherein a B content is within a range of 0.1-1.5 mass % inclusive, a V content is within a range of 0.05-1 mass % inclusive, and a ratio [B content/V content] is within a range greater than 1 and 30 or less, thereby achieving a piston ring (10) having higher wear resistance, cracking resistance, and peeling resistance. This alloy film (3) preferably further includes Ti, the Ti content being within a range greater than 0 mass % and 8 mass % or less. Such a piston ring (10) is preferably mounted on an engine that uses an alcohol fuel or an alcohol-containing fuel.

Provided is a piston ring (10) comprising a sliding surface (11) covered with a CrBVN alloy film (3), wherein a B content is within a range of 0.1-1.5 mass % inclusive, a V content is within a range of 0.05-1 mass % inclusive, and a ratio [B content/V content] is within a range greater than 1 and 30 or less, thereby achieving a piston ring (10) having higher wear resistance, cracking resistance, and peeling resistance. This alloy film (3) preferably further includes Ti, the Ti content being within a range greater than 0 mass % and 8 mass % or less. Such a piston ring (10) is preferably mounted on an engine that uses an alcohol fuel or an alcohol-containing fuel.

A cylinder of an internal combustion engine, having a cylinder liner and a cylinder piston guided in the cylinder liner The cylinder piston has multiple ring grooves delimited by ring webs and are separated by the ring webs. Each ring grooves receives a compression ring or an oil scraping ring. Each ring groove is delimited by an upper groove flank, a lower groove flank and a groove base, and each piston ring has a lower ring flank, an upper ring flank a ring back and a section which rests against a radially inner running surface of the cylinder liner. A depression is introduced into the lower groove flank of the at least one ring groove or each ring groove which receives a compression ring and/or into the lower ring flank of the piston ring designed as a compression ring.

A piston ring set for internal combustion (IC) engine is provided. The IC engine includes a cylinder having a liner and a finish on the liner. A piston having a crown and a set of grooves is disposed in the cylinder. A set of piston rings is disposed in the set of grooves. The piston rings are disposed in order from closest to the crown and include at least a first compression ring having free ends defining a first end gap, a second compression ring having free ends defining a second end gap. A nominal value of the first end gap of the first compression ring is greater than a nominal value of the second end gap of the second compression ring.

A combined oil control ring comprising a pair of annular side rails each having a gap, and an axially corrugated spacer expander arranged between the side rails; the corrugated spacer expander having on the inside seating tabs for pushing inner peripheral surfaces of the side rails; the side-rail-pushing surface of each seating tab being provided with a nitrided layer; an entire surface of each spacer expander except for those provided with the nitrided layer being coated with a plating film; and the plating film having Vickers hardness HV0.01 of 300 or less.

A combined oil control ring comprising a pair of annular side rails each having a gap, and an axially corrugated spacer expander arranged between the side rails; the corrugated spacer expander having on the inside seating tabs for pushing inner peripheral surfaces of the side rails; the side-rail-pushing surface of each seating tab being provided with a nitrided layer; an entire surface of each spacer expander except for those provided with the nitrided layer being coated with a plating film; and the plating film having Vickers hardness HV0.01 of 300 or less.