Method and device for determining an angled structure in the surface of a precision machined cylindrical work piece
First Claim
1. A method for operating a camera to determine a structure of machining marks on a surface of a cylindrically finely finished workpiece, the camera and the workpiece being mutually aligned, the method comprising the steps of:
- recording an image of surface characteristics of the workpiece; and
in order to determine a helically running structure of the machining marks, performing the steps of;
performing a Radon transformation of the image, and determining a helix angle of those of the machining marks that are helical;
rotating the workpiece;
recording a plurality of images if the surface characteristics of the workpiece at a constant twisting angle;
providing a plurality of Radon transforms by performing the Radon transformation for each one of the plurality of images;
extracting a Radon strip from each one of the plurality of Radon transforms;
juxtaposing the Radon strips of the Radon transforms of each one of the plurality of images in a Radon strip image; and
performing a correlation analysis of the juxtaposed Radon strips.
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Accused Products
Abstract
A method for determining a helical groove structure, for example in the form of flutes, in the surface of a finely finished cylindrical workpiece, in particular the ground mating bearing surface of radial shaft sealing rings, which is characterized in that a camera is used to record at least one image of the illuminated surface of the workpiece, which image reproduces the helical groove structure in the surface of the workpiece. A device for carrying out a method includes a CCD camera with a macrolens, a radial bearing device for the workpiece, an illuminating device and an image reading and image processing device.
57 Citations
14 Claims
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1. A method for operating a camera to determine a structure of machining marks on a surface of a cylindrically finely finished workpiece, the camera and the workpiece being mutually aligned, the method comprising the steps of:
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recording an image of surface characteristics of the workpiece; and
in order to determine a helically running structure of the machining marks, performing the steps of;
performing a Radon transformation of the image, and determining a helix angle of those of the machining marks that are helical;
rotating the workpiece;
recording a plurality of images if the surface characteristics of the workpiece at a constant twisting angle;
providing a plurality of Radon transforms by performing the Radon transformation for each one of the plurality of images;
extracting a Radon strip from each one of the plurality of Radon transforms;
juxtaposing the Radon strips of the Radon transforms of each one of the plurality of images in a Radon strip image; and
performing a correlation analysis of the juxtaposed Radon strips. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for operating a camera to determine a structure of machining marks on a surface of a cylindrically finely finished workpiece, the camera and the workpiece being mutually aligned, the method comprising:
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rotating the workpiece;
recording a plurality of images of surface characteristics of the workpiece at a constant twisting angle;
to determine a helically running structure of the machining marks, performing the following;
providing a plurality of Radon transforms by performing a Radon transformation for each one of the plurality of images;
extracting a Radon strip from each one of the plurality of Radon transforms;
juxtaposing the Radon strips of the Radon transforms of each one of the plurality of images in a Radon strip image;
performing a correlation analysis of the juxtaposed Radon strips; and
determining a helix angle of those of the machining marks that are helical;
independently of the Radon transformation, producing a Fourier transform of at least one of the plurality of images;
forming a periodogram from the Fourier transform;
filtering the periodogram in accordance with an operation of a comb filter;
determining a spacing parameter of the comb filter in conjunction with a maximization of a periodic power component;
calculating the periodic power component as a ratio of a proportion of the machining marks to the surface, wherein the spacing parameter of the comb filter corresponds to an estimated value of a periodic length of a helical groove structure; and
calculating a number of threads of the helical groove structure from the helix angle and the periodic length. - View Dependent Claims (14)
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Specification