A burnishing tool and a method of additively manufacturing components of the burnishing tool are provided. The burnishing tool includes a burnishing element for burnishing a workpiece. The burnishing element is positioned between an upper nozzle and a lower nozzle which are additively manufactured to define a plurality of internal fluid passageways for receiving, distributing, and discharging a burnishing fluid to facilitate cooling and/or lubrication of the burnishing element and/or the workpiece.

An ultrasonic roller burnishing system comprises a roller and a controller. The roller is configured to be pressed against a surface of a workpiece to a pressing depth, roll on the surface at a feed rate, and vibrate at an ultrasonic frequency under a back pressure. The roller is pressed and rolled by a motion unit which is driven by a drive motor. The vibrating of the roller is driven by an ultrasonic vibration unit with an input current inputted thereinto. The controller is configured to adjust at least one of the pressing depth, the back pressure, the input current and the feed rate based on an expected residual compressive stress and a real time output power of the drive motor, to generate a residual compressive stress in the workpiece which is in an expected range predetermined based on the expected residual compressive stress.

An ultrasonic roller burnishing system comprises a roller and a controller. The roller is configured to be pressed against a surface of a workpiece to a pressing depth, roll on the surface at a feed rate, and vibrate at an ultrasonic frequency under a back pressure. The roller is pressed and rolled by a motion unit which is driven by a drive motor. The vibrating of the roller is driven by an ultrasonic vibration unit with an input current inputted thereinto. The controller is configured to adjust at least one of the pressing depth, the back pressure, the input current and the feed rate based on an expected residual compressive stress and a real time output power of the drive motor, to generate a residual compressive stress in the workpiece which is in an expected range predetermined based on the expected residual compressive stress.

An expansion tool comprises a tool body for manipulating the tool, a drive module for driving the rotation of a cylindrical needle cage in the bore, the cylindrical needle cage having an axis of revolution about which the needle cage is configured to start to rotate in the bore, the needle cage comprising needles configured to move radially away from the axis of revolution so as to work-harden the bore as the needle cage is rotationally driven by the drive module. The expansion tool also comprises a rod having a burnisher configured to move the needles of the needle cage radially as the burnisher passes through the needle cage as a result of the translational movement of the rod. The rotation of the needle cage allows the entire internal surface of the bore to be work-hardened.

A method of imparting compressive residual stress to a first plurality of balls includes a) placing the balls between a first body having a first surface and a second body having a second surface, the first surface including a smooth contact portion, the smooth contact portion being substantially flat or convex and having a surface hardness greater than or equal to an initial surface hardness of the balls, b) imparting a compressive stress along a first diameter of the balls by pressing the first body toward the second body or the second body toward the first body or the first and second bodies toward one another with a force, and c) causing relative movement between the first surface and the second surface while maintaining the force at or above a minimum level to impart the compressive stress along other diameters of the balls different than the first diameter.

A method of imparting compressive residual stress to a first plurality of balls includes a) placing the balls between a first body having a first surface and a second body having a second surface, the first surface including a smooth contact portion, the smooth contact portion being substantially flat or convex and having a surface hardness greater than or equal to an initial surface hardness of the balls, b) imparting a compressive stress along a first diameter of the balls by pressing the first body toward the second body or the second body toward the first body or the first and second bodies toward one another with a force, and c) causing relative movement between the first surface and the second surface while maintaining the force at or above a minimum level to impart the compressive stress along other diameters of the balls different than the first diameter.

An automotive shaft fillet treating method including laser hardening a green machined fillet surface to a uniform depth d to induce compressive stresses into the surface, the surface extending the entire length l between outer edges of two undercut regions of the fillet, and applying additional compressive stress to the laser hardened surface via fillet rolling such that the uniform depth d is maintained along the entire length l during a subsequent grinding operation.

A method may comprise providing an M-flange of a gas turbine engine, wherein the M-flange may comprise a bolt hole therethrough defined by a bolt hole circumference between an inner diameter and an outer diameter of the M-flange; heating a mandrel; inserting the heated mandrel into the bolt hole such that an outer edge of the heated mandrel contacts the bolt hole circumference; and plastically deforming the bolt hole circumference to strengthen the bolt hole circumference in response to the applying the heated mandrel, producing a plastically deformed bolt hole.

A steel sheet includes a sheet thickness center part and a first surface layer softened part and a second surface layer softened part respectively arranged at two sides of the sheet thickness center part, wherein the first surface layer softened part and second surface layer softened part have 10 ?m or more average thicknesses and have average Vickers hardnesses of 0.90 times or less of the average Vickers hardness of a sheet thickness ? position, and the first surface layer softened part has an average Vickers hardness of 1.05 times or more the average Vickers hardness of the second surface layer softened part.

A method for coating a cylinder wall of an internal combustion engine, in which the cylinder wall is roughened prior to coating, such that the cylinder wall is compressed prior to roughening by plastic deformation.