Patent ID: 8863722

Claim:
A machining method for a cylinder block, comprising steps of: obtaining deformation amount of a data-acquisition bore, which is deformed after fastening of a cylinder head to a cylinder block, along a central axial direction; determining an approximate shape, which approximates a deformation shape of the data-acquisition bore, by setting a cross section of the approximate shape to be an approximately-true circle shape and changing a diameter of the approximately-true circle shape along the central axial direction in accordance with the deformation amount of the data-acquisition bore; and determining a shape, which is obtained by reversing a phase of a recess and a projection of the approximate shape about a predetermined cylindrical shape, as a machining shape of a bore, wherein a side cross section of the bore is set to have an approximately-circular truncated cone shape, and a diameter of the approximately-circular truncated cone shape is set to be larger from one surface to another surface.