In one aspect of the present invention, a method for manufacturing a bearing component includes: a preparation step of preparing a ring-shaped member of steel having a radially inner surface, a radially outer surface, and a thickness which is a distance between the radially inner surface and the radially outer surface; and a heat treatment step of performing a heat treatment to locally heat one of the radially inner surface and the radially outer surface to a heat treatment temperature and subsequently cool the one of the radially inner surface and the radially outer surface, the method satisfying S≥930/(0.3477 W.sup.2−1.594 W−0.804), where S represents an average temperature increasing rate (unit: ° C./sec) applied when the surface is heated and W represents the thickness (unit: mm).

A rack bar includes: a rack tooth row including a plurality of rack teeth meshing with pinion teeth; a hardened layer provided continuously over an entire circumference of the rack tooth row; and a center portion provided inside the hardened layer and having lower hardness than the hardened layer. When the rack bar is viewed in an axial direction of the rack bar, a depth of the hardened layer from the following positions i), ii), and iii) increases in this order: i) a bottom land of the rack teeth; ii) a side of the rack bar relative to the bottom land; and iii) a back of the rack bar relative to the bottom land.

A bearing bushing for a track has an annular shape including an inner peripheral surface, an outer peripheral surface, a first end face, and a second end face located axially opposite the first end face. The bearing bushing for a track includes an inner peripheral surface-side hardened layer formed to include the inner peripheral surface, an outer peripheral surface-side hardened layer formed to include the outer peripheral surface, a first end face-side hardened layer formed to include the first end face and having a region with a hardness of 63 HRC or more that has a thickness of 3 mm or more from the first end face, and an unhardened region lower in hardness than the inner peripheral surface-side hardened layer, the outer peripheral surface-side hardened layer, and the first end face-side hardened layer, and including at least the second end face. The bearing bushing is made of steel.

A bearing bushing for a track has an annular shape including an inner peripheral surface, an outer peripheral surface, a first end face, and a second end face located axially opposite the first end face. The bearing bushing for a track includes an inner peripheral surface-side hardened layer formed to include the inner peripheral surface, an outer peripheral surface-side hardened layer formed to include the outer peripheral surface, a first end face-side hardened layer formed to include the first end face and having a region with a hardness of 63 HRC or more that has a thickness of 3 mm or more from the first end face, and an unhardened region lower in hardness than the inner peripheral surface-side hardened layer, the outer peripheral surface-side hardened layer, and the first end face-side hardened layer, and including at least the second end face. The bearing bushing is made of steel.

The invention relates to a tool for a power tool, the tool having a longitudinal axis (L) and comprising a working section and a shaft with a connection end for connecting the tool to a tool holder of the power tool, wherein the shaft comprises at least one protruding structure protruding from the shaft. It is characterized in that at least within one of two halves (A, B) of the protruding structure, which are separated by a plane perpendicular to the longitudinal axis (L), the surface of the protruding structure has a finite gradient along a direction parallel to the longitudinal axis (L).

A track pad may include a base member and a roller path member extending from the base member. The roller path member may include a roller path surface for engaging with a roller of a machine. The roller path member may include a leading side and a trailing side in a direction of travel of the machine. The roller path member may include a hardened region that extends from the roller path surface and a body region adjacent the hardened region. The hardened region may have a greater hardness than the body region. The hardened region may have a uniform depth from the leading side to the trailing side of the roller path member.

A track pad may include a base member and a roller path member extending from the base member. The roller path member may include a roller path surface for engaging with a roller of a machine. The roller path member may include a leading side and a trailing side in a direction of travel of the machine. The roller path member may include a hardened region that extends from the roller path surface and a body region adjacent the hardened region. The hardened region may have a greater hardness than the body region. The hardened region may have a uniform depth from the leading side to the trailing side of the roller path member.

A carburized shaft part having a predetermined composition, a C content at a surface layer part of a mass % of 0.60 to 1.00%, at least one hole at an outer circumferential surface, a total volume ratio of martensite and retained austenite of 97% or more at a structure at a position of a 1 mm depth from the outer circumferential surface in an axial direction of the hole and a position of a 20 μm depth from the surface of the hole, a maximum retained austenite volume ratio (R1) of 10.0 to 30.0% at a position of a 1 mm depth from the outer circumferential surface in the axial direction of the hole and a range up to a 200 μm depth from the surface of the hole, and a retained austenite reduction ratio of 20% or more found from R1 and the retained austenite volume ratio (R2) at a position of a 1 mm depth from the outer circumferential surface in the axial direction of the hole and a position of a 20 μm depth from the surface of the hole by the formula (A): Δγ=(R1−R)/R1×100.

A heating apparatus (2) includes a high frequency power supply (3), a left conductive plate (4), a right conductive plate (5), a left heating coil (11), and a right heating coil (12). The left heating coil (11) includes a left conductor portion (21). The left conductor portion (21) faces a gear tooth (7a) of a helical gear (7) and extends in a direction orthogonal to the direction in which the gear tooth (7a) extends. The left heating coil (11) includes a focusing magnetic body (31) which focuses magnetic flux in the left conductor portion (21) and concentrates the magnetic flux on a surface of the gear tooth (7a). The left heating coil (11) includes an upper inducing magnetic body (32) which induces a part of the magnetic flux flowing in a tooth root of the gear tooth (7a) into a tooth tip of the gear tooth (7a).

A heating apparatus (2) includes a high frequency power supply (3), a left conductive plate (4), a right conductive plate (5), a left heating coil (11), and a right heating coil (12). The left heating coil (11) includes a left conductor portion (21). The left conductor portion (21) faces a gear tooth (7a) of a helical gear (7) and extends in a direction orthogonal to the direction in which the gear tooth (7a) extends. The left heating coil (11) includes a focusing magnetic body (31) which focuses magnetic flux in the left conductor portion (21) and concentrates the magnetic flux on a surface of the gear tooth (7a). The left heating coil (11) includes an upper inducing magnetic body (32) which induces a part of the magnetic flux flowing in a tooth root of the gear tooth (7a) into a tooth tip of the gear tooth (7a).