CN103017684A - Device and method for detecting roundness and straightness of cylindrical holes by coaxial light - Google Patents

Abstract

The invention relates to a device and a method for detecting roundness and straightness of cylindrical holes by coaxial light and belongs to the technical field of optical detection. The prior art is low in detection precision and narrow in detection range and possibly causes damage to the surface of a cylindrical hole being detected. The device is disposed between a detecting laser source and a camera. An iris diaphragm, a light barrier ring, a conical lens and a frosted glass imaging screen are axially arranged in sequence. The bottom of the conical lens faces to the light barrier ring and is provided with a central through hole. The method includes: the cylindrical hole to be detected is located between the conical lens and the frosted glass imaging screen and is axial with coaxial light; the distance of hollow beams from outer wall to inner wall is changed by regulating the iris diaphragm; the hollow beams emerging from a conical surface of the conical lens converge and reflect once at different sectional positions of the cylindrical hole being detected, and light ring images for each section are present on the frosted glass imaging screen successively; the images are acquired by the camera and processed by a computer, roundness of different sectional positions of the cylindrical hole to be detected is calculated first by the least square circle method, and straightness of the cylindrical hole is obtained then.

Description

The device and method of axis light test column hole circle degree and linearity

Technical field

The present invention relates to the device and method of a kind of axis light test column hole circle degree and linearity, under noncontact, nondestructive prerequisite, the concentric laser beam of utilizing the center to open foraminate Conical Lenses formation detects circularity and the linearity in part post hole in real time, belongs to the optical detective technology field.

Background technology

In precision or ultraprecise field of machining, how to control the circularity in post hole and linearity concerning cooperation, the running accuracy of part, be directly connected to friction, vibration, noise etc., and then affect serviceable life and the energy consumption of parts.Therefore, need accurately evaluation post hole circle degree and linearity, evaluation result not only provides foundation for the examination of part, and helps to improve parts machining precision and assembly precision.Its prerequisite of described evaluation is the detection of post hole circle degree and linearity.

Described post hole refers to the cylinder endoporus, and post hole circle degree refers to the actual circle contour of seized part endoporus and the deviate of evaluating basic circle.A kind of existing Method of Roundness Assessment relevant with the present invention is minimum two-multiply law, and as the evaluation basic circle, circularity △ C is the method with Least Square Circle:

ΔC=D _max-D _min （1）

In the formula: D _MaxFor different angles collection point, cross section, tested post hole with respect to Least Square Circle 1 center of circle O ₀Ultimate range, D _MinFor different angles collection point, cross section, tested post hole with respect to Least Square Circle 1 center of circle O ₀Minor increment, as shown in Figure 1.

Make up Least Square Circle 1 by least square method, namely find the solution the central coordinate of circle value X of Least Square Circle ₀, Y ₀With radius of circle R ₀Minimal value, establishing collection point, different angles place, cross section, tested post hole is D to the distance in the Least Square Circle center of circle _i, i is the collection point sequence number, that is:

$F(X_0,{\mathrm{<figure-callout\; id="0"\; label="Y"\; filenames="HDA00002712950900011.png,HDA00002712950900032.png"\; state="\{\{state\}\}">Y</figure-callout>}}_0,R_0)=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{D}_i^2=\min ---\left(2\right)$

The line of n collection point i is actual measurement circle 2, and the real contour line in certain cross section namely is at the D that tries to achieve according to formula (2) _iIn comprise D _MaxAnd D _Min, try to achieve again the circularity of tested post hole section according to formula (1).The cross section sequence number is j if make, formula (1) writing $\mathrm{\&Delta;}{C}_j=D_{j_{\max }}-D_{j_{\min }}.$

Post hole linearity refers to the actual axis of seized part endoporus and the deviate of evaluating baseline.Set up rectangular coordinate system with the evaluation baseline as Z axis, the central coordinate of circle of the Least Square Circle in each cross section, post hole that above-mentioned roundness calculation is obtained is made as O _0j(X _0j, Y _0j), the linearity △ S in post hole is so:

ΔS=2d _max （3）

$d_j=\sqrt{{\mathrm{<figure-callout\; id="2"\; label="X\; oj"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">X</figure-callout>}}_{\mathrm{oj}}^{}+Y_{\mathrm{oj}}^2}---\left(4\right)$

In the formula: d _jBe the Least Square Circle center of circle O in j cross section _0jTo the distance of evaluation baseline, d _MaxBe the ultimate range of the Least Square Circle center of circle in n the cross section to the evaluation baseline, as shown in Figure 2, the Least Square Circle center of circle O in each cross section, tested post hole _0jLine 3 be the actual measurement axis in tested post hole, with d _MaxFor radius, take the minimum envelop face of evaluation baseline as the cylinder 4 of axis as all Least Square Circle centers of circle of envelope.

The existing technology that gathers the positional information of the tested post a plurality of collection point i of cross-sectional perimeter different angles place in hole is a kind of optical detecting method that adopts the trolley type measurement mechanism, is seen in one piece of HeFei University of Technology's academic dissertation of being shown by what enormous legendary fish, which could change into a roc (on May 8th, 2004).As shown in Figure 3, it detects workpiece is Large Diameter Long Pipes 5, at base 6 two ends a draw-gear 7 is arranged respectively, Large Diameter Long Pipes 5 places on the base 6, and between two draw-gears 7, measurement dolly 8 is put into Large Diameter Long Pipes 5, is pulled on Large Diameter Long Pipes 5 inwalls by draw-gear 7 to go and back running.In measuring dolly 8, detection head 9 is axially launched detection laser along Large Diameter Long Pipes 5, this detection laser is rear along Large Diameter Long Pipes 5 radial propagations by reflective mirror 10 reflections, spot drops on Large Diameter Long Pipes 5 tube walls, this spot absorbs along the camera system in the tested gauge head 9 of original light path backpropagation, rest on Large Diameter Long Pipes 5 interior a certain positions and measure dolly 8 this moment, but, reflective mirror 10 drives rotating 360 degrees by drive motor 11, camera system has been finished the point sampling on the tube wall in Large Diameter Long Pipes 5 some cross sections, and send computing machine 12 to, and measure step-length of dolly 8 every walkings, computing machine 12 will obtain the point sampling on the tube wall in a cross section.Process by image, the different light path information entrained according to each sampled point are extracted on certain cross section at a distance of the coordinate of equal angular some collection points, calculate the circularity in this cross section according to formula (1), (2).Calculate again the central coordinate of circle in each cross section, obtained the linearity of Large Diameter Long Pipes 5 endoporus by the central coordinate of circle data in these cross sections by formula (3), (4).But, described detection scheme has its deficiency: the one, and this scheme is only applicable to the detection of heavy caliber endoporus, if the endoporus bore is less, measures dolly and then can't enter; The 2nd, measuring dolly does not have own special-purpose, accurate track, and walking roll angle and measured workpiece shape error all can reduce accuracy of detection; The 3rd, measure dolly and also may in the process of walking, scratch the measured workpiece inside surface.

Summary of the invention

In order to improve post hole circle degree and Linearity surveying precision, enlarge post bore open sensing range, avoid detecting the damage to the measured workpiece inside surface that may cause, we have invented the device and method of a kind of axis light test column hole circle degree and linearity.

The present invention's axis light test column hole circle degree and the device of linearity have detection laser light source 13, video camera 14 is connected with pattern process computer 15, as shown in Figure 4, it is characterized in that, between detection laser light source 13 and video camera 14, iris 16, baffle vane 17, Conical Lenses 18, frosted glass imaging screen 19 be arranged in co-axial alignment successively; Conical Lenses 18 bottom surfaces are towards baffle vane 17, and there is through hole at Conical Lenses 18 centers, iris 16 aperture Φ ₁Maximal value less than or equal to Conical Lenses 18 clear aperture Φ ₂, as shown in Figure 5, baffle vane 17 external diameter φ ₁' greater than Conical Lenses 18 through hole bore φ ₂1 ~ 2 mm, baffle vane 17 internal diameter φ ₁" equal Conical Lenses 18 through hole bore φ ₂

The present invention's axis light test column hole circle degree and the method for linearity are a kind of minimum two-multiply laws, it is characterized in that, become the axis light that the hollow beam by the solid light beam at center and periphery consists of after by iris 16, baffle vane 17 from the collimator and extender light of detection laser light source 13, as shown in Figure 6; Tested post hole 20 between Conical Lenses 18 and frosted glass imaging screen 19 and coaxial with axis light, tested post hole 20 towards the end face position of Conical Lenses 18 for detecting starting point A, being endpoint detection B towards the end face position of frosted glass imaging screen 19; Hollow beam inwall in the axis light of maintenance incident Conical Lenses 18 bottom surfaces is to the distance B of optical axis ₁Constant, change the hollow beam outer wall to the distance B of inwall by adjusting iris 16 ₂, converge from the hollow beam of Conical Lenses 18 conical surface outgoing, certainly detecting starting point A primary event occuring to 20 different cross section places, the tested post of endpoint detection B hole, on frosted glass imaging screen 19, successively present the ring of light image in each cross section; The directly imaging on frosted glass imaging screen 19 of solid light beam in the axis light is shown in Fig. 7 ~ 9; Gather described all images and be sent to pattern process computer 15 by video camera 14; Carrying out image by pattern process computer 15 processes, the inner boundary of ring of light image represents post to be measured hole 20 cross section real contour lines, determine the coordinate figure of collection point, different angles place on the approximate circumference of described inner boundary, calculate first at last the circularity at 20 different cross section places, post to be measured hole according to minimum two-multiply law, obtain on this basis again the linearity in this post hole.

Its technique effect of the present invention is, compared to existing technology, obtain to calculate the data message aspect of post hole circle degree, linearity, the present invention adopts noncontact not damaged mode, by the solid light beam in the axis light post hole is located, can be finished again the more preliminary extraction of data at the frosted glass imaging screen by each the detection sectional plane primary event in the post hole of the hollow beam in the axis light, there are not parts to enter the post hole, therefore, the aperture in tested post hole can be very little, also can not damage the post hole surface that Precision Machining is crossed, accuracy of detection also significantly improves simultaneously.

Description of drawings

Fig. 1 adopts minimum two-multiply law to find the solution post hole circle degree principle schematic.Fig. 2 adopts minimum two-multiply law to find the solution post hole linearity principle schematic.Fig. 3 is existing trolley type measurement mechanism and testing process synoptic diagram.Fig. 4 is the present invention's axis light test column hole circle degree and apparatus structure and the detection mode synoptic diagram of linearity, and this figure is simultaneously as Figure of abstract.Fig. 5 is the present invention's axis light test column hole circle degree and the device partial structurtes synoptic diagram of linearity.Fig. 6 is the present invention's axis light test column hole circle degree and the method synoptic diagram of linearity.Fig. 7 ~ Fig. 9 is the present invention's axis light test column hole circle degree and the method test column hole different cross section situation synoptic diagram of linearity.Figure 10 is tested post bore open X in the method for the present invention's axis light test column hole circle degree and linearity _h, length X _lWith the graph of a relation of detection starting point A to the distance L of Conical Lenses.Figure 11 is tested post hole length X in the method for the present invention's axis light test column hole circle degree and linearity _l, bore X _hWith hollow beam outer wall in the axis light distance B to inwall ₂Graph of a relation.

Embodiment

Conical Lenses 18 has following relational expression with testing conditions:

$X_l=\frac{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">D</figure-callout>}}_2\sqrt{1-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">n</figure-callout>}}^2{\sin }^2\mathrm{\&theta;}}}{\cos \mathrm{\&theta;}(n\sin \mathrm{\&theta;}\cos \mathrm{\&theta;}-\sin \mathrm{\&theta;}\sqrt{1-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">n</figure-callout>}}^2{\sin }^2\mathrm{\&theta;}})}---\left(5\right)$

$X_h=2\frac{\frac{n\sin \mathrm{\&theta;}}{\sqrt{1-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">n</figure-callout>}}^2{\sin }^2\mathrm{\&theta;}}}-\tan \mathrm{\&theta;}}{1+\tan \mathrm{\&theta;}\frac{n\sin \mathrm{\&theta;}}{\sqrt{1-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">n</figure-callout>}}^2{\sin }^2\mathrm{\&theta;}}}}(L-{\mathrm{<figure-callout\; id="3"\; label="D"\; filenames="HDA00002712950900012.png"\; state="\{\{state\}\}">D</figure-callout>}}_3\tan \mathrm{\&theta;}-\frac{D_1}{\frac{\frac{n\sin \mathrm{\&theta;}}{\sqrt{1-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">n</figure-callout>}}^2{\sin }^2\mathrm{\&theta;}}}-\tan \mathrm{\&theta;}}{1+\tan \mathrm{\&theta;}\frac{n\sin \mathrm{\&theta;}}{\sqrt{1-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">n</figure-callout>}}^2{\sin }^2\mathrm{\&theta;}}}}}+{\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA00002712950900011.png"\; state="\{\{state\}\}">D</figure-callout>}}_1\tan \mathrm{\&theta;})---\left(6\right)$

In the formula: θ is the circular cone base angle of Conical Lenses 18, and n is the refractive index of Conical Lenses 18 glass, D ₁Be the distance of the hollow beam inwall in the axis light of incident Conical Lenses 18 bottom surfaces to optical axis, D ₂Be the distance of described hollow beam outer wall to inwall, D ₃Be the conical bottom radius surface of Conical Lenses 18, L is the distance that Conical Lenses 18 is arrived in tested post hole 20, and specifically the circular cone bottom surface of Conical Lenses 18 is to the distance that detects starting point A, X _lBe tested post hole length, specifically detect starting point A to the distance of endpoint detection B, X _hFor detecting bore, as shown in Figure 6.

Collimator and extender optical wavelength from detection laser light source 13 is 532 nm, beam diameter 20 mm.Iris 16 aperture Φ ₁Setting range be 0 ~ 20 mm, baffle vane 17 external diameter φ ₁' be 5 mm, baffle vane 17 internal diameter φ ₁" be 3 mm, Conical Lenses 18 through hole bore φ ₂Also be 3 mm.The saturating 18 glass trades mark of conscope are K9, refractive index n=1.5168, circular cone base angle θ=10 °, conical bottom radius surface D ₃=28.36 mm, effectively clear aperture Φ ₂=22 mm.Hollow beam from Conical Lenses 18 conical surface outgoing converges, penetrate the mode uniform irradiation on 20 surfaces, tested post hole to plunder, primary event is occuring to 20 different cross section places, the tested post of endpoint detection B hole certainly detecting starting point A, reflected light carries 20 the type information in tested post hole, therefore, this reflected light is thing light light beam 21, and shown in Fig. 4, Fig. 7 ~ 9, thing light light beam 21 presents the ring of light image in each cross section at frosted glass imaging screen 19; Tested post hole 20 is to the distance L of Conical Lenses 18, and namely the circular cone bottom surface of Conical Lenses 18 is 110 mm to the distance that detects starting point A, and frosted glass imaging screen 19 is 150 mm to the distance of endpoint detection B; Frosted glass imaging screen 19 is of a size of 200 * 200 mm ²The directly imaging on frosted glass imaging screen 19 of solid light beam in the axis light, this solid light beam is reference beam 22 namely.

According to above-mentioned parameter and formula (5), (6) as can be known, when changing tested post hole 20 to the distance L of Conical Lenses 18 in 25 ~ 500 mm scopes, the present invention can adapt to bore X _hThe detection in the tested post hole 20 of=1 ~ 100 mm, as shown in figure 10.When in 2.5 ~ 10 mm scopes, changing the hollow beam outer wall to the distance B of inwall by adjusting iris 16 ₂, the present invention can adapt to length X _lThe detection in the tested post hole 20 of=25 ~ 110 mm, as shown in figure 11.If change the parameter of Conical Lenses 18, comprise circular cone base angle θ, refractive index n, conical bottom radius surface D ₃, the present invention can adapt to wider bore X _h, length X _lThe detection in tested post hole 20.

The present invention adopts the Photoshop image processing software to process the image that gathers:

1, the physical size value of the representative of single pixel in the image of determining to gather;

2, picture centre is exactly frosted glass imaging screen 19 centers, is the center of central light beam equally, determines the cell coordinate of picture centre, namely the coordinate in the Photoshop coordinate system;

3, set up again the X-Y-Z rectangular coordinate system take image center as initial point, light shaft coaxle in Z axis and the present invention's the device, the real contour line in the cross section corresponding with every width of cloth image is positioned on the X-Y coordinate plane as plane curve, the interval equal angular is determined several collection points on the approximate circumference of real contour line, such as interval 22.5 ^oDetermine 16 collection points, determine first the cell coordinate of these collection points in the Photoshop coordinate system, try to achieve the collection point pixel at the coordinate figure of X-Y-Z rectangular coordinate system according to the physical size value of the representative of single pixel again, adopt least square method to obtain the central coordinate of circle O of the least square basic circle of each cross section real contour line _0j(X _0j, Y _0j), j is the cross section sequence number, relatively D is determined at the coordinate figure of X-Y-Z rectangular coordinate system in each collection point on the real contour line in certain cross section _Jmax, D _Jmin, according to formula

Try to achieve the circularity Δ C in certain cross section _jCentral coordinate of circle O at the least square basic circle of different cross section _0j(X _0j, Y _0j) with the deviation d of picture centre point coordinate O (0,0) _jIn determine maximal value deviation d _Max, according to formula Δ S=2d _MaxTry to achieve the linearity Δ S in tested post hole 20.

Claims (5)

1. the device of an axis light test column hole circle degree and linearity, has detection laser light source (13), video camera (14) is connected with pattern process computer (15), it is characterized in that, between detection laser light source (13) and video camera (14), iris (16), baffle vane (17), Conical Lenses (18), frosted glass imaging screen (19) be arranged in co-axial alignment successively; Conical Lenses (18) bottom surface is towards baffle vane (17), and there is through hole at Conical Lenses (18) center, iris (16) aperture Φ ₁Maximal value less than or equal to Conical Lenses (18) clear aperture Φ ₂, baffle vane (17) external diameter φ ₁' greater than Conical Lenses (18) through hole bore φ ₂1 ~ 2 mm, baffle vane (17) internal diameter φ ₁" equal Conical Lenses (18) through hole bore φ ₂

2. the device of axis light test column hole circle degree according to claim 1 and linearity is characterized in that, iris (16) aperture Φ ₁Setting range be 0 ~ 20 mm, baffle vane (17) external diameter φ ₁' be 5 mm, baffle vane (17) internal diameter φ ₁" be 3 mm; Conical Lenses (18) through hole bore φ ₂Be 3 mm, conscope thoroughly (18) glass trade mark is K9, refractive index n=1.5168, circular cone base angle θ=10 °, conical bottom radius surface D ₃=28.36 mm, effectively clear aperture Φ ₂=22 mm; Frosted glass imaging screen (19) is of a size of 200 * 200 mm ²

3. the method for an axis light test column hole circle degree and linearity, the method is a kind of minimum two-multiply law, it is characterized in that, become the axis light that the hollow beam by the solid light beam at center and periphery consists of after by iris (16), baffle vane (17) from the collimator and extender light of detection laser light source (13); Tested post hole (20) is positioned between Conical Lenses (18) and the frosted glass imaging screen (19) and is coaxial with axis light, tested post hole (20) towards the end face position of Conical Lenses (18) for detecting starting point A, being endpoint detection B towards the end face position of frosted glass imaging screen (19); Hollow beam inwall in the axis light of maintenance incident Conical Lenses (18) bottom surface is to the distance B of optical axis ₁Constant, change the hollow beam outer wall to the D of the distance of inwall by adjusting iris (16) ₂, converge from the hollow beam of Conical Lenses (18) conical surface outgoing, certainly detecting starting point A primary event occuring to different cross section place, the tested post of endpoint detection B hole (20), at the upper ring of light image that successively presents each cross section of frosted glass imaging screen (19); Solid light beam in the axis light is directly in the upper imaging of frosted glass imaging screen (19); Gather described all images and be sent to pattern process computer (15) by video camera (14); Carrying out image by pattern process computer (15) processes, the inner boundary of ring of light image represents cross section, post to be measured hole (20) real contour line, determine the coordinate figure of collection point, different angles place on the approximate circumference of described inner boundary, calculate first at last the circularity at different cross section place, post to be measured hole (20) according to minimum two-multiply law, obtain on this basis again the linearity in this post hole.

4. the method for axis light test column hole circle degree according to claim 3 and linearity is characterized in that, changes tested post hole (20) to the distance L of Conical Lenses (18) in 25 ~ 500 mm scopes, and the method can adapt to bore X _hThe detection in the tested post hole (20) of=1 ~ 100 mm; When in 2.5 ~ 10 mm scopes, changing the hollow beam outer wall to the distance B of inwall by adjusting iris (16) ₂, the method can adapt to length X _lThe detection in the tested post hole (20) of=25 ~ 110 mm.

5. the method for axis light test column hole circle degree according to claim 3 and linearity is characterized in that, adopts the Photoshop image processing software to process the image that gathers:

(1) the physical size value of the representative of single pixel in the image of determining to gather;

(2) picture centre is exactly frosted glass imaging screen (19) center, is the center of central light beam equally, determines the cell coordinate of picture centre, namely the coordinate in the Photoshop coordinate system;

(3) set up again the X-Y-Z rectangular coordinate system take image center as initial point, light shaft coaxle in Z axis and the present invention's the device, the real contour line in the cross section corresponding with every width of cloth image is positioned on the X-Y coordinate plane as plane curve, the interval equal angular is determined several collection points on the approximate circumference of real contour line, determine first the cell coordinate of these collection points in the Photoshop coordinate system, try to achieve the collection point pixel at the coordinate figure of X-Y-Z rectangular coordinate system according to the physical size value of the representative of single pixel again, adopt least square method to obtain the central coordinate of circle O of the least square basic circle of each cross section real contour line _0j(X _0j, Y _0j), j is the cross section sequence number, relatively D is determined at the coordinate figure of X-Y-Z rectangular coordinate system in each collection point on the real contour line in certain cross section _Jmax, D _Jmin, according to formula Try to achieve the circularity Δ C in certain cross section _jCentral coordinate of circle O at the least square basic circle of different cross section _0j(X _0j, Y _0j) with the deviation d of picture centre point coordinate O (0,0) _jIn determine maximal value deviation d _Max, according to formula Δ S=2d _MaxTry to achieve the linearity Δ S in tested post hole 20.

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