An evaluation work piece includes at least one of a part (B) or (G), and at least one of a part (A), (C), (D), (E), or (F). (A) is a vertical level difference part. (B) is a direction reversing part at which a direction of movement of a tool in a height direction is reversed when the tool is used for machining of a three-dimensional object including a curved surface. (C) is a corner part at which a direction of movement of the tool changes. (D) is a flat surface part. (E) is a boundary part between a flat surface and a curved surface with a changing curvature. (F) is a curved surface part having a curved surface with a changing curvature. (G) is a curved surface part at which command points are aligned regularly between adjacent tool paths on a curved surface. At least one of the part (B) or (G) is included in a cut spherical body part. A reference surface for a three-dimensional measuring machine is arranged around the cut spherical body part. At least one of the part (A), (C), (D), (E) or (F) is arranged outside the reference surface.

According to one example, a CNC machine tool system may perform error compensation for improving the accuracy of the geometry (or form) of a machined workpiece to, for example, better than 2 micrometers. To do so, a first machined workpiece may be created using the CNC machine tool system. The CNC machine tool system may create the machined workpiece by jig grinding. Following the creation of the first machined workpiece, metrology of the workpiece error may then be performed on the machined workpiece. The metrology of the workpiece error may be used to create a corrected toolpath trajectory for re-machining. This corrected toolpath trajectory may then be utilized by the CNC machine tool system to machine a second machined workpiece having a geometry (or form) with an accuracy of, for example, better than 2 micrometers.

An evaluation work piece which is machined with a multi-axis machine tool that includes three linear axes and one or more rotary axes includes: at least one of a curved surface portion in which the inclination of a tool is changed, a boundary portion of two regions of a flat surface which is machined at different angles of the tool and which includes the two adjacent regions and a corner portion in which the amount of movement of the rotary axis is larger than the amount of movement of a tool tip point. The curved surface portion is preferably formed to be a free curved surface. Preferably, the evaluation work piece includes: a stage-shaped machined portion; and a twisted machined portion which is formed on the stage-shaped machined portion, the boundary portion is formed in the front surface of the stage-shaped machined portion and the curved surface portion and the corner portion are formed in the twisted machined portion.

A tool path generation method includes inputting a first function derived from a polynomial expression including a plurality of coefficients representing a first curved surface, generating a first tool path based on the first function, inputting the first tool path to an NC device of a machine tool and machining a workpiece by relative movement between a tool and a workpiece along the first tool path, measuring the shape of the workpiece at a plurality of measurement points on a surface of the machined workpiece, calculating, for each of the measurement points, a symmetrical position with respect to the first curved surface in a direction perpendicular to the first curved surface as a correction point, obtaining a second function representing a second curved surface based on a series of position data of the correction points, and generating a second tool path based on the second function.

Disclosed is a machining method by turning at least one surface of an ophthalmic lens, using a turning machine having at least one geometrical defect. The method includes a step (101-104) of determining a turning configuration for machining by turning the at least one surface of the ophthalmic lens, the turning configuration including turning parameters and machine defects parameters associated to the turning parameters.

Disclosed is a method for deducing geometrical defects of an optical article turning machine, including a defect value deducing step, during which at least one geometrical defect value is deduced based at least on an indicative information of an optical and/or geometrical data related to an optical and/or geometrical characteristic of a checking piece (10).

A spatial accuracy correction apparatus performs a spatial accuracy correction of a positioner displacing a displacer to a predetermined set of spatial coordinates using a measurable length value measured by an interferometer and a measurable value of the set of spatial coordinates of the displacement body that is measured by the positioner. The measured length value and the measured value for each measurement point are acquired by displacing the displacement body to a plurality of measurement points in order, one or more repeated measurements are conducted for at least one of the plurality of measurement points being measured after conducting measurement of the measured length value and the measured value for each of the plurality of measurement points, and the plurality of points are measured again when a repeat error of the measured length value is equal to or greater than a threshold value.

A method that corrects an error in positioning in a positioning mechanism by using a measurable length value measured by a laser interferometer and a measured value for spatial coordinates measured by the positioning mechanism. The method includes a measurement step in which a retroreflector affixed to a displacer is displaced to a plurality of measurement points, and the measured length value and the measured value at each of the measurement points is acquired; and a parameter calculation step in which a correction parameter is calculated based on the measured value, the measured length value, and the coordinates of a rotation center of the tracking-type laser interferometer. A first correction constant is applied to the measured length value for each measurement line, and a second correction constant different from the first correction constant is applied to the coordinates of the rotation center of the interferometer for each measurement line.

An evaluation work piece comprises at least one of parts (A) to (G) as follows on a surface machined by a machine tool: (A) a vertical level difference part having a vertical level difference, and flat surfaces arranged on both sides of the vertical level difference; (B) a direction reversing part at which a direction of movement of a tool in a height direction is reversed when the tool is used for machining of a three-dimensional object including a curved surface; (C) a corner part at which a direction of movement of the tool changes; (D) a flat surface part; (E) a boundary part between a flat surface and a curved surface with a changing curvature; (F) a curved surface part having a curved surface with a changing curvature; and (G) a curved surface part at which command points are aligned regularly between adjacent tool paths on a curved surface.

In a method for determining a deviation of a spatial orientation of a beam axis (S) of a beam processing machine from a spatial nominal orientation (S0) of the beam axis (S), contour sections (KA1, KB2) are cut with a processing beam into a test workpiece from two sides of the workpiece. The contour sections (KA1, KB2) extend parallel to a nominal orientation of a rotation axis (B, C), where the rotation axis is to be calibrated. The contour sections (KA1, KA2) are probed from one side of the test workpiece by a measuring device for determining the spatial position of the contour sections (KA1, KB1). Deviation of the spatial orientation of the beam axis (S) of the beam processing machine from the spatial nominal orientation (S0) is determined based on the spatial positions of the contour sections (KA1, KB1).