DE102007008604A1 - Structures i.e. honed structures, evaluation method, involves separating target characteristics and error characteristics for separation of target and error structures, and fragmenting original image into corrugated-and contact area image - Google Patents

Abstract

The method involves separating target characteristics and error characteristics for separation of target and error structures. An original image is fragmented into a corrugated-and contact area image and a remaining image during the structures separation. The original image is obtained with the help of white light interferometry from optical three dimensional data. Measured three dimensional data or three dimensional image is processed, and original image relevant parameters are extracted.

Description

The The invention relates to a method for evaluating structures Surfaces, in particular honing structures on cylinder liners.

From the German patent DE 103 02 055 B4 is an interferometric measuring device for measuring the surface of an object is known, which is designed as a white light interferometer. From the German patent application DE 10 2005 023 212 A1 A method and apparatus for fast and accurate white light interferometry is known that can rapidly measure surfaces with interferometric accuracy.

task The invention is a method for evaluating structures on surfaces according to the preamble of claim 1, the comprehensive close-to-series, non-destructive quality assurance of surfaces, in particular of honed cylinder liners, allows.

The Task is on a method for evaluating structures Surfaces, in particular honing structures on cylinder liners, solved by the fact that in a structure separation target and Error characteristics, in particular target and error structures, separated by disassembling an original image. In the structure separation Measured 3D data or 3D images are further processed. Out relevant parameters are extracted from the original image. By objective Evaluation of function-relevant structural elements with characteristics becomes a comprehensive close-to-production, non-destructive quality assurance of honed cylinder liners of all types. In addition, a possibility of tolerance specification and drawing entry for the characteristics provided. The inventive method allows easy identification of target and error structures and the evaluation of their characteristics, whereby a targeted intervention in a production process is made possible. In the structure separation (separation) are set and error structures using high-resolution 3D surface measurements recorded separately.

One preferred embodiment of the method is characterized characterized in that the original image in a Riefen- and contact surface image and a residual image is decomposed. This will in a simple way and Perform an identification of the relevant structural elements mathematical and image-analytical method allows. In particular, a depth, area and volumetric Calculation of features allows.

One Another preferred embodiment of the method is characterized in that the original image with the help of White light interferometry obtained from 3D optical data becomes. For this purpose a suitable interferometer is used. As an interferometer is called an optical device that is under exploitation of interference phenomena of light for precision measurements is used.

The inventive method allows including the following benefits: Unique, comprehensive drawing specification; close-to-production, non-destructive quality assurance, short intervention times; Targeted intervention options in a manufacturing process; simplified introduction of new ones Materials or honing processes; as well as the recognition of Structural changes after engine run. This will in the construction a purposeful design of surface structures exact description of the characteristics as well as a faster finding of the optimal honing parameters (tool, process) for new developments allows.

Further Advantages, features and details of the invention will become apparent the following description, with reference to the drawing various embodiments described in detail are.

there demonstrate:

1 the principle of structure separation on honed surfaces;

2 a sketch for the definition of the honing angle and

3 a table with relevant parameters for quality assurance.

With The method according to the invention makes it possible to with the help of 3D characteristics an objective Structural element-oriented evaluation of a surface perform. It can be features and dimensions be captured using conventional stylus methods or can not be determined with a microscope.

The basis for the 3D evaluation is a surface image with the smallest possible deviations from the actual surface. By means of several ring comparisons, it has been demonstrated in the context of the present invention that the measurement method of white-light interferometry or white-light interferometry is most suitable for the measurement of honing structures. Therefore all parameters defined here are based on white light interferometry measurements. In order to ensure the comparability of the measurement results, the measurement parameters must be coordinated with the surface metrology (PWT). Basis of the evaluation are measuring fields, which with an optical resolution <1.2 microns were recorded. The camera resolution has to be adapted to the optical resolution.

The statistical safety for the determination of the measured quantities requires a minimum necessary evaluation area for each characteristic is specified. This should be off consist of several non-contiguous measuring fields. Before the 3D evaluation, a robust formula removal (cylindrical deduction) respectively.

The Basis of all parameters defined here a structure separation. The goal of the structure separation is the separate Evaluation of target and error structures of a honed surface.

In 1 is the principle of structure separation on honed surfaces with the help of three images. In the upper original image, the original measuring surface is shown with a honing structure. Two arrows indicate that the original image is separated into a ridge and contact surface image (bottom right) and a residual image (bottom left) in the structure separation by a separation. The scoring and contact surface image comprises directional structures. The residual image includes the difference between the original and the scored image.

Out The structure separation generates additional images. A binarized Scored image serves as the masking basis for a feature extraction. One Contact surface image includes identified as contact surfaces Areas. A metal jacket surrounds identified as a metal jacket Areas. A pore image comprises areas identified as pores. A marbling picture includes areas identified as marbling.

The Characteristics of the structure separation are divided in score, contact area and error characteristics.

The groove characteristics include honing marks. Honorable notes can be rising (with a positive increase) or falling (with a negative increase). All Honriefen outside a honing angle tolerance are referred to as Querriefen. Honing marks are divided into 4 types, the distinguishing criterion is the average Honriefenquerschnitt:
Type A all grooves with a larger cross-section than the lower limit of Type D;
Type B all grooves with an average cross-section greater than or equal to 30 μm ² ;
Type C all grooves with an average cross-section greater than or equal to 10 μm ² and less than 30 μm ² ;
Type D all grooves with an average cross-section greater than or equal to 2 μm ² and less than 10 μm ² ;

The Scoring characteristics can be used for each type of query can be determined.

In 2 the definition of a honing angle is shown. The angle between rising honing marks Hs and falling honing marks Hf enclosing the axis-perpendicular direction A is called an overlap angle α. The honing angle α / 2 corresponds to half the overlap angle α. The honing angle is determined from a radial projection of a Fourier transformation. The minimum necessary evaluation area is 1.5 mm ² .

parameters to the Honriefen frequency are from the frequency distribution derived from the honors. Such characteristics are the honeycomb density or honeycomb surface, the scatter gauge Honriefenabstand, the uniformity and the transverse groove proportion.

The Honriefendichte or Honriefenfläche is the area of Honriefen in the main directions in% based on the evaluation area. It is determined separately for rising and falling honors in the picture. The basis of calculation is the binarized honey triangular image. The minimum necessary evaluation area is 6 mm ² .

The distance measure Honrug distance is determined from the distribution of the Honriefenabstände for each Honriefentyp. The scattering ratio is described as the quotient of the standard deviation and the mean honing distance. The basis of calculation is the binarized honey triangular image. The minimum necessary evaluation area is 6 mm ² .

The uniformity of the expression of both Honrichtungen is the ratio of smaller Honriefendichte to higher Honriefendichte in%. It is ideally 100%. The basis of calculation is the binarized honey triangular image. The minimum necessary evaluation area is 6 mm ² .

The transverse groove proportion is the ratio of the area of all grooves outside the two main directions to the sum of the grooves within the main directions in% and is ideally 0%. As transverse letters, all grooves outside the honing angle tolerance are considered. The basis of calculation is the binarized honey triangular image. The minimum necessary evaluation area is 6 mm ² .

parameters for the expression of the honing marks are the Honriefenquerschnitt, the honing volume, the honing width and the honking depth.

The Honing cross section is calculated per Honriefe from the original image in combination with the binarized scored image as single Honriefenvolumen / single Honriefenlänge and in μm ² indicated. The honeycomb cross-section is the basis for the classification of types B, C, D.

The average honing cross section is the sum of all Honriefen cross sections per type or direction / number of grooves per type or direction [μm ² ]. The maximum honing cross section is related to a single letter (type A) [μm ² ]. The minimum necessary evaluation area is 6 mm ² .

The Honriefenvolumen is compared to the environment by a Robust envelope surface closed at the top. The Calculation is made from the original image in combination with the binarized one Called image.

The average honing volume is calculated as the sum of all Honriefen volumes per type or direction / number of grooves per type or direction normalized to 1 mm ² [μm ³ / mm ² ]. The maximum honing volume is related to a single call (type A) [μm]. The minimum necessary evaluation area is 6 mm ² .

The Honing width is combined per honors from the original image calculated with the binarized scored image as a single honing area / single honing distance and in μm.

The average honing width is the sum of all honing widths per type or direction / number of grooves per type or direction [μm]. The maximum honing width is related to a single letter (type A) [μm]. The minimum necessary evaluation area is 6 mm ² .

The Honecrust depth is combined per Honriefe from the original image Calculated with the binarized scored image as a single honing volume / single Honriefenfläche.

The average honing note depth is the sum of all honing note depths per type or direction / number of grooves per type or direction [μm]. The maximum honing note depth is related to a single letter (type A) [μm]. The minimum necessary evaluation area is 6 mm ² .

Contact surface characteristics are the contact roughness and the flat spot portion. Contact surfaces are limited by grooves of types B, C and D, pores and the edge of the measuring field. The contact surfaces are combined from the original image determined with the binarized scoring pattern and the pore image.

The total contact area results from the sum of all contact areas in% to the evaluation area. The mean contact surface is the total contact area / number of contact surfaces [μm ² ].

Contact roughness is the fine structure of a contact surface. It is calculated from the mean value of all Pt values in the contact surface area in the axial direction and expressed in μm. The minimum necessary evaluation area is 6 mm ² .

The flatness rate rates the slopes of the contact surfaces. It is calculated by forming the slope distribution of the slopes in the axial direction in the contact surface areas. The flats share is the percentage of the distribution where the amount of the slope is less than 0.02. The minimum necessary evaluation area is 6 mm ² .

Error structural characteristics are the metal jacket, marbling and micropores and eruptions. Error structures are material and / or by individual production steps conditionally. Within certain limits of expression affect fault structures the function of the cylinder liner is not. The expression the fault structures are described with characteristics, can be specified for the limits.

When Sheet metal jacket are called raised structures in the groove area. The detection takes place in the residual image. For this, the areas are determined by a certain amount higher than the Riefengrund.

Because of the different effect on the function, two types of sheet metal jackets are distinguished:
Type A: Sheet metal shells that are above or close to the adjacent contact surface plane are referred to as sheet metal shells Type A. Metal jacket volume positive. Pos / neg
Type B: Sheet metal shells that lie below the adjacent contact surface level are referred to as type B metal sheaths. Metal jacket volume Distance volume negative.

The Distinguishing between sheet metal jackets type A and B takes place by: a robust reference surface with the original and the binarized Riefenbild is combined. Sheet metal shells above the reference surface are the type A, metal shells below the reference surface are assigned to type B. The robust reference surface is the basis for determining volume, area and height the metal coats.

The maximum metal jacket volume is based on the individual metal jacket and is given in μm ³ only for Type A. The maximum metal jacket height is based on the individual metal jacket and is given in μm only for type A. The metal jacket volume is based on all type A metal sheaths. It is calculated from the sum of all metal jacket volumes of type A, normalized to 1 mm ² . [μm ³ / mm ² ] The metal jacket surface is covered by all type A or type B metal sheaths and is given in% of the evaluation area. The mini necessary evaluation area is 6 mm ² .

When Marbling becomes desk-like elevations in the contact surface area designated. Detection takes place in the residual image in combination with the binarized groove and pore image.

The Marmorierungsfläche includes all detected as marbling structures which are higher than the surrounding contact surface plane and is given in% to the evaluation area. The marbling volume is calculated from the sum of all volumes of the structures detected as marbling and normalized to 1 mm ² . [μm ³ / mm ² ] The minimum necessary evaluation area is 6 mm ² .

micropores and outbreaks are not differentiated in the evaluation. As pores are depressions in the contact surface area referred to below a fixed level. The Detection takes place in the residual image in combination with the binarized one Called image. Large-scale casting defects and outbreaks are not rated with the following parameters.

The maximum pore volume is related to the single pore and is given in μm ³ . The maximum pore area is related to the single pore and is given in μm ² . The pore area is related to all pores and is given in% to the evaluation area. The pore volume is related to all pores and normalized to 1 mm ² . [μm ³ / mm ² ] The mean pore distance is given in μm. The minimum necessary evaluation area is 6 mm ² .

In 3 Relevant parameters for quality assurance are summarized in the form of a table. The systematics of the abbreviations used are explained for the area-related parameters using the example of the parameter increasing / decreasing. With a maximum metal jacket volume of type A (SHBVmax_A), S stands for an international designation for surface characteristics (Surface). H stands for honing structure. B stands for metal jacket. V (expression) stands for volume. max stands for the maximum value of the characteristic. _A stands for type identification, here type A.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10302055 B4 [0002]
• DE 102005023212 A1 [0002]

Claims (3)

Method for evaluating structures on surfaces, in particular of honing structures on cylinder surfaces, characterized in that, in a structure separation, setpoint and error characteristics, in particular setpoint and error structures, are separated by decomposing an original image. Method according to claim 1, characterized in that that the original image into a Riefen- and contact surface image and a residual image is decomposed. Method according to one of the preceding claims, characterized in that the original image by means of white light interferometry obtained from 3D optical data.