A piston ring is produced from a main body made of steel or cast steel and comprising a running face, an inner circumferential surface, upper and lower flank regions, and transition regions from the running face to the respective flank region, by coating the running face and the transition regions with a first chromium layer, removing this first chromium layer at the running face down to the base material of the main body, providing at least the running face of the layer-free main body with a nitride layer, and, finally, coating the running face and the transition regions with at least one further chromium layer.

A piston ring providing improved performance during operation, including reduction in blowby gases and improved oil control, is provided. The piston ring includes an upper layer, a lower layer, and a middle layer each formed from a powder metal material. An exposed sharp first corner is present between an upper ring surface and an upper outer diameter surface, and an exposed sharp second corner is present between a lower ring surface and a lower outer diameter surface. The piston ring also comprises a coating including diamond-like carbon (DLC). The DLC coating is inlaid. Thus, the coating is disposed on the middle layer but is spaced from the upper and lower corners, so that the upper and lower corners of the piston ring are exposed.

A magnetorheological support method for blisk processing is disclosed. In the method, a fork structure and a soft film are used to wrap magnetorheological fluid. The magnetorheological fluid is used for flow filling under certain pressure. The bulged soft film can conduct shape matching on the surface of a blisk blade. The magnetorheological fluid can be cured through magnetic field excitation, thereby ensuring the flexible support for a weak rigid component. Electric permanent magnets are symmetrically arranged at both ends of the fork structure to construct a uniform magnetic field that can realize a global excitation of magnetorheological fluid, so that the magnetorheological fluid works in a shear mode to achieve damping force controlling by magnetic field. The solid-liquid conversion of the magnetorheological fluid is controlled by an electric permanent magnet field.

A piston ring providing improved performance during operation, including reduction in blowby gases and improved oil control, is provided. The piston ring includes an upper layer, a lower layer, and a middle layer each formed from a powder metal material. An exposed sharp first corner is present between an upper ring surface and an upper outer diameter surface, and an exposed sharp second corner is present between a lower ring surface and a lower outer diameter surface. The piston ring also comprises a coating including diamond-like carbon (DLC). The DLC coating is inlaid. Thus, the coating is disposed on the middle layer but is spaced from the upper and lower corners, so that the upper and lower corners of the piston ring are exposed.

A piston ring is produced from a main body made of steel or cast steel and comprising a running face, an inner circumferential surface, upper and lower flank regions, and transition regions from the running face to the respective flank region, by coating the running face and the transition regions with a first chromium layer, removing this first chromium layer at the running face down to the base material of the main body, providing at least the running face of the layer-free main body with a nitride layer, and, finally, coating the running face and the transition regions with at least one further chromium layer.

A piston ring is produced from a main body made of steel or cast steel and comprising a running face, an inner circumferential surface, upper and lower flank regions, and transition regions from the running face to the respective flank region, by coating the running face and the transition regions with a first chromium layer, removing this first chromium layer at the running face down to the base material of the main body, providing at least the running face of the layer-free main body with a nitride layer, and, finally, coating the running face and the transition regions with at least one further chromium layer.

A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.

A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.

A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.

A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.