A mold machining method using an endmill, the contour of a cross section of the mold being concave and continuous in an area, a ratio of the maximum to the minimum of radius of curvature of the contour of a portion of the area (a first area) being 2 or greater, and a blade of the endmill having a second area where the contour of a cross section is similar to the contour of the first area, the method comprising the steps of determining a spiral path of the endmill such that each point of the first area is machined by a portion of the second area, corresponding to said each point in the similarity, and a radial interval between the spiral tool path is maximized while keeping surface roughness of the machined mold at or below a predetermined value; and machining the mold along the path.

A mold machining method using an endmill, the contour of a cross section of the mold being concave and continuous in an area, a ratio of the maximum to the minimum of radius of curvature of the contour of a portion of the area (a first area) being 2 or greater, and a blade of the endmill having a second area where the contour of a cross section is similar to the contour of the first area, the method comprising the steps of determining a spiral path of the endmill such that each point of the first area is machined by a portion of the second area, corresponding to said each point in the similarity, and a radial interval between the spiral tool path is maximized while keeping surface roughness of the machined mold at or below a predetermined value; and machining the mold along the path.

A portable helical milling unit has a tool, an eccentric spindle, an outer sleeve, a sleeve housing, and a plurality of transmission mechanisms used to provide power. The eccentric spindle is detachably provided in an output section of the outer sleeve. Each of the eccentric spindle and the outer sleeve has a pre-set eccentricity. The tool is in connection with an eccentricity adjustment mechanism. The outer sleeve is installed in the sleeve housing. The outer sleeve is in connection with a first transmission mechanism and a third transmission mechanism. The eccentric spindle is in connection with a second transmission mechanism. All eccentric spindles have the same shape, can be installed in the outer sleeve and can be quickly replaced, so as to achieve precise and large-range adjustment of the eccentricity, thereby expanding the aperture range of processed holes, and improving processing quality and efficiency.

Certain embodiments of the present disclosure provide an acoustic inlet barrel of an engine. The acoustic inlet barrel may include an inner barrel configured to provide a boundary for directing airflow through the engine. The inner barrel may include an inner face sheet separated from an outer face sheet by an acoustic core. The inner barrel may include a plurality of elongated, non-circular perforations formed through the inner face sheet.

Certain embodiments of the present disclosure provide an acoustic inlet barrel of an engine. The acoustic inlet barrel may include an inner barrel configured to provide a boundary for directing airflow through the engine. The inner barrel may include an inner face sheet separated from an outer face sheet by an acoustic core. The inner barrel may include a plurality of elongated, non-circular perforations formed through the inner face sheet.

A frictional drive railway wheel truing system comprising a master lift and drive arm spaced from a slave lift and drive arm extending from within a railway pit for lifting a pair of opposed railway wheels off railway rails. Each master and slave drive assembly comprising frictional drums to turn a railway wheel from a wheel flange. A master and slave lathe assembly moveable along an axis parallel to a rotational axis of the frictional drums; each master and slave lathe assembly having a cutting bit positioned to engage a tread and a flange of a railway wheel in a cut mode at a location superior to the contact area of said frictional drums and railway wheel; and a hold down device fixing rotation of a railway wheel to a predetermined axis during a wheel truing operation.

A frictional drive railway wheel truing system comprising a master lift and drive arm spaced from a slave lift and drive arm extending from within a railway pit for lifting a pair of opposed railway wheels off railway rails. Each master and slave drive assembly comprising frictional drums to turn a railway wheel from a wheel flange. A master and slave lathe assembly moveable along an axis parallel to a rotational axis of the frictional drums; each master and slave lathe assembly having a cutting bit positioned to engage a tread and a flange of a railway wheel in a cut mode at a location superior to the contact area of said frictional drums and railway wheel; and a hold down device fixing rotation of a railway wheel to a predetermined axis during a wheel truing operation.

A milling device for machining a slot into an inner surface of a casing for a gas turbine engine. The milling device includes a frame assembly including multiple structural guides configured to engage structural features on the inner surface of the casing to maintain an axial position of the milling device relative to a longitudinal axis of the casing. The milling device also includes a milling cutter coupled to the frame assembly. The milling device is configured to be displaced in a circumferential direction relative to the longitudinal axis to machine the slot, via the milling cutter, along the inner surface of the casing in the circumferential direction.

A milling device for machining a slot into an inner surface of a casing for a gas turbine engine. The milling device includes a frame assembly including multiple structural guides configured to engage structural features on the inner surface of the casing to maintain an axial position of the milling device relative to a longitudinal axis of the casing. The milling device also includes a milling cutter coupled to the frame assembly. The milling device is configured to be displaced in a circumferential direction relative to the longitudinal axis to machine the slot, via the milling cutter, along the inner surface of the casing in the circumferential direction.

Provided is a machining apparatus capable of improving the positioning accuracy of a machining tool as compared to conventional machines. A machining apparatus 1 includes a rotating tool, a machining tool provided on an outer periphery of the rotating tool, and a spindle head adapted to rotatably support the rotating tool. The machining apparatus includes a driving portion configured to move the spindle head in a direction perpendicular to an axis of rotation R of the rotating tool, a position sensor configured to measure a position of the spindle head on a plane perpendicular to the axis of rotation R, and a control unit configured to control the driving portion so as to move the machining tool in a direction perpendicular to the axis of rotation R of the rotating tool on the basis of the position of the spindle head.