CN102914479A - Automatic Brinell hardness testing method - Google Patents
Automatic Brinell hardness testing method Download PDFInfo
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- CN102914479A CN102914479A CN2012102892184A CN201210289218A CN102914479A CN 102914479 A CN102914479 A CN 102914479A CN 2012102892184 A CN2012102892184 A CN 2012102892184A CN 201210289218 A CN201210289218 A CN 201210289218A CN 102914479 A CN102914479 A CN 102914479A
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Abstract
The automatic Brinell hardness testing method has the advantages that firstly, a manual detection method is replaced by using computer image identification, the Brinell hardness is tested rapidly and accurately, and the defects in the prior art that the manual testing method needs manual interference, is strong in objectiveness, low in testing precision and has high requirements on the quality of the surface of a piece to be tested, and the like; secondly, indentation images are obtained by using an internal optical system, having the advantages of low cost, high image quality and convenient carrying operation; thirdly, the shape feature of the indentation is scientifically scanned by using an image processing technique, and the fine change of the edge of the indentation can be reflected objectively, and the noise edge caused by the poor surface quality is eliminated by using the curvature change of the edge of the indentation, and the precision in testing the hardness is improved; and fourthly, a computer image testing system compiled according to the method provided by the invention is good in expansion capability, is high in adaptation to the surface qualities of various testing pieces, and has the characteristics of being high in automation degree, rapid in operation and convenient and simple.
Description
Technical field
The present invention relates to a kind of Brinell hardness automatic measuring method, belong to the computer image processing technology field.A kind of method of utilizing image processing techniques to carry out the Brinell hardness quick automatic determining specifically.
Background technology
The ultimate principle that Brinell hardness is measured: a standard hardness spherical indenter is imposed certain pressure, is pressed into the testee surface, shed load after testee with a residual circular impression, determine the hardness number of material according to the size of impression.The size of hardness number press head diameter, load and impression diameter is calculated according to formula and is got.Wherein, impression diameter is used microscope artificial observation reading usually, or after using digital camera to obtain indentation image, manually chooses the impression frontier point and calculate impression diameter.They mainly depend on eye-observation, require the tester to possess certain working experience and professional skill, determination efficiency is lower, and cause easily personal error, and the result who causes the different operating and measure between the person is different.
At present, Brinell hardness impression diameter quick automatic determining method is being sought in this area.A kind of scheme is to utilize the CCD camera to obtain indentation image, utilization image processing techniques realization automatically accurately measuring the impression size.But because measured test specimen surface texturisation is different, institute gathers and often has more noise contribution in the indentation image, has reduced the degree of accuracy of accuracy and the specimen hardness measurement of indentation edge extraction.
In order to guarantee the accurate measurement of impression diameter, require the test specimen surface to answer flat-satin in the national standard (GB/T231.1-2009), and do not have oxide skin and extraneous dirt etc., and recommendation form surface roughness parameter Ra is not more than 1.6 μ m.Therefore, need by mechanical means (upper grinding machine) or manual method measured surface to be carried out cutting down, make the measured surface roughness of sample reach inspection side slat spare.The surface roughness value is lower after the finishing, and when gathering indentation image, its image quality is better, indentation image edge clear (such as Fig. 2).But effects on surface carries out cutting down, has both consisted of additional operation link, also makes to measure the cost rising.
Summary of the invention
In order more accurately to measure material hardness, the invention provides a kind of scheme, wherein, utilize computer image processing technology, in conjunction with the impression shape facility, obtain quickly and accurately the shape information of impression, scientifically describe the slight change of impression shape, thereby the testing staff is freed from the heavy duplication of labour.
The variety of issue that exists in order to overcome present detection method the object of the present invention is to provide a kind of machine vision technique that utilizes to realize fast, accurately assay method of Brinell hardness.In the present invention, at first utilize image processing techniques to extract indentation edge, extracted the impression shape facility, then by describing the slight change of impression shape, reject pseudo-edge, keep the impression true edge, final by calculating the impression diameter size, realize the Accurate Measurement of Brinell hardness.
According to an aspect of the present invention, provide a kind of Brinell hardness automatic measuring method, it is characterized in that comprising:
Gather the image of the impression on the test specimen;
Extract the edge of the described image of described impression;
Reject the pseudo-edge in the described edge;
Generation impression circle;
The hardness of calculation testing piece.
Description of drawings
Fig. 1 is Image Acquisition according to an embodiment of the invention and treating apparatus connection diagram;
Fig. 2 has shown the image through a smooth surface impression behind the cutting down;
Fig. 3 is indentation image and edge extracting after the general industry polishing according to an embodiment of the invention;
Fig. 4 is rust face indentation image according to an embodiment of the invention and edge extracting.
Embodiment
According to one embodiment of present invention, provide a kind of Brinell hardness automatic method for measuring, it has fast, accurately, stable, need not the advantage such as manual intervention fully, to overcome the deficiencies in the prior art.
To achieve these goals, Brinell hardness automatic measuring method according to an embodiment of the invention comprises:
-collection test specimen indentation image
Use sclerometer that the sintered carbide ball of certain diameter is applied test force Specimen surface, after the regulation retention time, the removal test force, impression appears in the test specimen surface.As shown in Figure 1, (portable) Brinell hardness analyzer 1 vertically is positioned over the surface of test specimen 2, gathers indentation image information on the test specimen surface with portable Brinell hardness analyzer 1, and input computing machine 3.
-extraction indentation edge
Common industrial sanding apparatus is processed test surfaces, and the surface roughness value is higher, and the indentation image marginal portion is fuzzy such as Fig. 3 (a) and Fig. 4 (a).And through after the image analysis processing, obtain corresponding indentation edge shown in Fig. 3 (b) and Fig. 4 (b).
The pseudo-edge of-rejecting impression
Because the test specimen surface quality is not high, causes the indentation edge noise spot more, has the part pseudo-edge, does not namely belong to the edge of true impression.After needing to reject pseudo-edge, justify match with true edge.
, the indentation edge each point is asked for curvature, and asks the curvature changing value so that rounded edge produces the characteristics of sudden change for noise spot, the reacting condition of curvature the situation of change of outline line, the curvature of circle contour changes comparatively smooth, changing value is less than predetermined value (such as 0.3).And there is part in noise spot, has the curvature mutation phenomenon.Therefore, in according to one embodiment of present invention, judge and the rejecting pseudo-edge by following steps:
A. the point (such as upper left point) on the impression profile (as counterclockwise), is followed the tracks of the impression profile as starting point in a direction, carries out the sampling of interval predetermined number (such as 10) pixel,
B. calculate the curvature k of certain some p of impression profile.Computation process is as follows:
k=θ
2-θ
1
Wherein, (x
p, y
p) be the coordinate of some p; Upper left as starting point with outline line, by counterclockwise outline line being followed the tracks of, interval i (such as i=10) pixel obtains two neighbouring sample point (x of current point
P-i,y
P-i), (x
P+i, y
P+i); θ
j(j=1,2) are the grazing angle of corresponding sampled point;
C. add up the curvature changing value continuously less than the sampled point of predetermined changing value (such as 0.3),
D. judge whether accumulative total surpasses a predetermined accumulative total numerical value (such as 10), belongs to arc section if "Yes" is then judged related pixel, belongs to pseudo-edge if "No" is then judged related pixel.
E. reject pseudo-edge.
-generation impression circle
After rejecting pseudo-edge, keep one section or multi-section circular arc on the impression profile, arc section is carried out match, thereby obtain the impression fitting circle, such as Fig. 3 .c and Fig. 4 .c.
-calculating test specimen hardness
Can calculate the hardness of test specimen according to impression match diameter of a circle and correlation parameter, computing method as shown in Equation (1).
According to the actual result of the Brinell hardness assay method of this embodiment, the hardness number precision reaches 0.01HBW, and impression diameter is to 0.0001mm resolution, and measures impression and show that the result only needs less than 1 second.
Advantage of the present invention comprises:
1. utilize computer picture recognition to replace the manual detection method, can measure Brinell hardness quick, objective, exactly, overcome in the prior art scheme need manual intervention, subjectivity is strong, accuracy of detection is low, treat the test block surface quality requires high defective;
2. the present invention adopts internal optics system acquisition indentation image, has that cost is low, picture quality is high and the advantage such as the operation that is easy to carry;
3. utilize image processing techniques scientifically to describe the impression shape facility, can reflect objectively the slight change of indentation edge, and utilize indentation edge curvature to change, reject by the poor noise edge that causes of surface quality, finally improve the degree of accuracy of Determination of Hardness;
4. measure system according to the computer picture of the method for the invention establishment, also have preferably extended capability.Fitness to all kinds of test specimen surface quality is high, has automaticity height, quick, the easy characteristics of operation.
Claims (10)
1. Brinell hardness automatic measuring method is characterized in that comprising:
Gather the image of the impression on the test specimen (2);
Extract the edge of the described image of described impression;
Reject the pseudo-edge in the described edge;
Generation impression circle;
The hardness of calculation testing piece (2).
2. according to claim 1 method, the step that it is characterized in that gathering the image of the impression on the test specimen (2) comprises:
Brinell hardness analyzer (1) is vertically placed the surface of test specimen (2),
With the lip-deep indentation image information of Brinell hardness analyzer (1) collection test specimen (2), and with indentation image input information computing machine (3).
3. according to claim 2 method, the step at edge that it is characterized in that extracting the described image of described impression comprises:
Industrial grinding process is carried out on surface to test specimen (2).
4. according to claim 3 method is characterized in that the step of rejecting the pseudo-edge in the described edge comprises:
A. a point on the impression profile is followed the tracks of the impression profile as starting point in a direction, carries out the sampling of the pixel of interval predetermined number;
B. calculate the curvature of the sampling pixel points of impression profile;
C. add up the curvature changing value continuously less than the sampled point of predetermined curvature changing value;
D. judge whether accumulative total surpasses a predetermined accumulative total numerical value, belongs to arc section if "Yes" is then judged related pixel, belongs to pseudo-edge if "No" is then judged related pixel;
E. reject pseudo-edge.
5. according to claim 4 method is characterized in that the step of described generation impression circle comprises:
The arc section of rejecting the impression profile that keeps behind the pseudo-edge carries out match, thereby obtains the impression fitting circle.
6. according to claim 5 method is characterized in that the step of calculation testing piece (2) hardness comprises:
According to the load value of described impression match diameter of a circle and input, calculate the hardness of test specimen.
7. according to claim 4 method is characterized in that:
Described predetermined curvature changing value is 0.3,
Described predetermined accumulative total numerical value is 10.
8. method one of according to claim 1-7 is characterized in that further comprising:
Apply test force by the sintered carbide ball to certain diameter and described sintered carbide ball is pressed into the surface of described test specimen (2) with sclerometer, and after the retention time that keeps being scheduled to,
The removal test force,
Thereby the surface at test specimen (2) forms described impression.
9. according to claim 8 method is characterized in that:
Described Brinell hardness analyzer (1) is portable Brinell hardness analyzer.
10. according to claim 6 method is characterized in that:
The step of the curvature of the sampling pixel points of described calculating impression profile comprises;
Get
k=θ
2-θ
1
Wherein, k is described curvature, (x
p, y
p) be the coordinate of some p; Upper left as starting point with outline line, by counterclockwise outline line being followed the tracks of, an i pixel in interval obtains two neighbouring sample point (x of current point
P-i, y
P-i), (x
P+i, y
P+i); θ
j(j=1,2) are the grazing angle of corresponding sampled point;
The step that described load value according to described impression match diameter of a circle and input calculates the hardness of test specimen is undertaken by following formula:
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| CN2012102892184A CN102914479A (en) | 2012-08-14 | 2012-08-14 | Automatic Brinell hardness testing method |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103364293A (en) * | 2013-07-19 | 2013-10-23 | 徐州豪立电子有限公司 | Portable material Brinell hardness measurement instrument and control method thereof |
| CN104964890A (en) * | 2015-05-14 | 2015-10-07 | 东莞市中旺精密仪器有限公司 | One-piece terminal application-based hardness detection method |
| CN107796718A (en) * | 2017-10-13 | 2018-03-13 | 郑显锋 | Brineling system and method |
| CN112014252A (en) * | 2020-09-02 | 2020-12-01 | 徐州工程学院 | Brinell hardness field measuring device for small-diameter pipe |
| CN112945704A (en) * | 2021-03-16 | 2021-06-11 | 八都机械锻造(苏州)有限公司 | Brinell hardness online detection system for intelligent factory |
| CN113052787A (en) * | 2019-12-27 | 2021-06-29 | 中核北方核燃料元件有限公司 | Automatic identification device and method for riser of ball blank |
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| CN101377457A (en) * | 2007-08-30 | 2009-03-04 | 上海电气集团上海电机厂有限公司 | Method for measuring brinell hardness |
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Patent Citations (1)
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| CN101377457A (en) * | 2007-08-30 | 2009-03-04 | 上海电气集团上海电机厂有限公司 | Method for measuring brinell hardness |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103364293A (en) * | 2013-07-19 | 2013-10-23 | 徐州豪立电子有限公司 | Portable material Brinell hardness measurement instrument and control method thereof |
| CN104964890A (en) * | 2015-05-14 | 2015-10-07 | 东莞市中旺精密仪器有限公司 | One-piece terminal application-based hardness detection method |
| CN104964890B (en) * | 2015-05-14 | 2018-06-05 | 东莞市中旺精密仪器有限公司 | Hardness detection method based on integral type terminal applies |
| CN107796718A (en) * | 2017-10-13 | 2018-03-13 | 郑显锋 | Brineling system and method |
| CN113052787A (en) * | 2019-12-27 | 2021-06-29 | 中核北方核燃料元件有限公司 | Automatic identification device and method for riser of ball blank |
| CN112014252A (en) * | 2020-09-02 | 2020-12-01 | 徐州工程学院 | Brinell hardness field measuring device for small-diameter pipe |
| CN112014252B (en) * | 2020-09-02 | 2023-03-14 | 徐州工程学院 | Brinell hardness field measuring device for small-diameter pipe |
| CN112945704A (en) * | 2021-03-16 | 2021-06-11 | 八都机械锻造(苏州)有限公司 | Brinell hardness online detection system for intelligent factory |
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Application publication date: 20130206 |