A turning device with static bar includes a motor, a driving shaft and a sleeve, which defines a seat for temporarily accommodating at least one portion of the bar being machined. A machining tool is coupled directly or indirectly on the sleeve. A secondary shaft is interposed between the driving shaft and the sleeve and is coupled to the screw of a first assembly constituted by a first recirculating-ball screw and a respective first lead screw integral with the sleeve. The sleeve and first assembly are coaxial and the driving shaft axis is parallel to and separate from the common axis of the sleeve and first assembly.

The device includes an adjustment element coupled to a pusher shaft, which through the secondary shaft.

makes the screw translate and the assembly lead screw rotate, with consequent rotation of the sleeve and a movement in a radial direction of the tool.

A round hole machining method and a round-hole machining device in which machining can be accurately performed regardless of the wear of an edge tool. A non-round hole machining device includes: a machining load data acquisition section for obtaining machining load data corresponding to a machining load acting on the cutting edge of a cutting tool when boring a bore in a cylinder block; a machined shape prediction section for predicting a machined shape of the workpiece by utilizing the obtained machining load data and elastic deformation amounts at respective positions on the workpiece; and a motor control section for machining the workpiece so as to form an inverted shape, that is, a shape formed by inverting the predicted machined shape with respect to a target shape.

A round hole machining method and a round-hole machining device in which machining can be accurately performed regardless of a residual stress caused by casting. An out-of-round hole machining device, which carries out inner diameter machining for a bore in a cast cylinder block includes the following: a stress deformation amount correspondence table that stores, for each portion of the cylinder block, a stress deformation amount based on stress that resides in the cylinder block during casting; a machining shape prediction section that predicts the machining shape on the basis of the stress deformation amount read from the stress deformation amount correspondence table; and a motor control unit that reverses the predicted machining shape with respect to a target shape and carries out reverse machining on a workpiece.