Abstract: A carrier for forming an electrophotographic image is provided. The carrier comprises a core particle and a coating layer coating the core particle. The coating layer contains chargeable particles and a dispersant. The carrier has an apparent density of from 2.0 g/cm3 or greater but less than 2.5 g/cm3.

Abstract: To provide a gear machining apparatus capable of correcting a tooth trace error without using a special tool when a hob cutter is cantilever-supported. A gear machining apparatus includes a hob cutter machining a tooth profile on a workpiece, a tool spindle device rotatably cantilever-supporting the hob cutter, a workpiece spindle device rotatably supporting the workpiece, a driving device moving the tool spindle device and the workpiece spindle device relatively to each other, a measuring device measuring the value corresponding to a bending amount of the hob cutter or a rotation synchronization shift of the workpiece spindle device with respect to the tool spindle device and a correction processing unit correcting a cutting amount of the hob cutter T or the rotation synchronization shift of the workpiece spindle device with respect to the tool spindle device based on the value measured by the measuring device.

Abstract: An electrophotographic developer is provided. The electrophotographic developer comprises a toner and a carrier. The toner contains alumina particles. The carrier comprises a core particle and a resin layer coating a surface of the core particle. The carrier has a volume average particle diameter (Dv) of from 45 to 70 ?m and a bulk density of from 2.1 to 2.5 g/cm3.

Abstract: A machine tool includes a workpiece holder, a tool holder holding working tools that includes a hob cutter used in a rough machining and a skiving cutter used in a finish machining, a tool magazine, a tool replacing device replacing one of the working tools mounted on the tool holder with the other of working tools housed in the tool magazine, a rough machining controlling section performing the rough machining on the workpiece, a tool measuring device measuring a position of a blade in a rotation direction of the skiving cutter, an angle correcting section correcting a rotation angle of the skiving cutter based on a result measured by the tool measuring device, and placing a tooth space formed in the workpiece and an edge tip of the blade in a position corresponding to each other, and a finish machining controlling section by which workpiece is finish machined.

Abstract: To provide a gear machining device and a gear machining method which achieve machining of tooth flanks having different torsion angles with high degree of accuracy. In a gear machining device, a side surface of a tooth of a gear includes a first tooth flank and a second tooth flank having a different torsion angle from the first tooth flank, a cutting blade of a machining tool has a blade traces having a torsion angle determined based on a torsion angle of the second tooth flank and an intersection angle between a rotation axis of a workpiece and a rotation axis of the machining tool so as to allow the second tooth flank to be machined on the pre-machined first tooth flank.