CN112529869A - Valve sleeve throttling square hole detection method - Google Patents
Valve sleeve throttling square hole detection method Download PDFInfo
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- CN112529869A CN112529869A CN202011444969.XA CN202011444969A CN112529869A CN 112529869 A CN112529869 A CN 112529869A CN 202011444969 A CN202011444969 A CN 202011444969A CN 112529869 A CN112529869 A CN 112529869A
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- 238000001514 detection method Methods 0.000 title claims description 14
- 238000000034 method Methods 0.000 claims abstract description 19
- 230000000007 visual effect Effects 0.000 claims abstract description 15
- 239000000523 sample Substances 0.000 claims description 2
- 238000005259 measurement Methods 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 1
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/0002—Inspection of images, e.g. flaw detection
- G06T7/0004—Industrial image inspection
- G06T7/0006—Industrial image inspection using a design-rule based approach
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T5/00—Image enhancement or restoration
- G06T5/70—Denoising; Smoothing
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/10—Segmentation; Edge detection
- G06T7/13—Edge detection
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- Computer Vision & Pattern Recognition (AREA)
- Quality & Reliability (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention relates to a method for detecting a throttling square hole of a valve sleeve, which comprises the steps of firstly adopting a three-coordinate measuring head to calibrate a measuring system, utilizing a visual image measuring head to obtain a square hole image of the throttling square hole of the valve sleeve, obtaining a boundary point of the throttling square hole and fitting the boundary line through denoising and binarization processing, calculating the length and width of the throttling square hole of the valve sleeve, then offsetting the boundary line, and judging whether four corners of the throttling square hole meet the requirements of sharp edges or not; and finally, detecting the size of the relative throttling square hole by rotating the measuring head, and judging whether the throttling square meets the requirement of the coplanarity of the hole. The invention can accurately measure the size, the sharp edge and the coplanarity requirement of the throttling square hole of the valve sleeve, and has high measuring speed and high measuring result precision.
Description
Technical Field
The invention relates to the technical field of measurement, in particular to a valve sleeve throttling square hole visual detection method.
Background
The valve core and the valve sleeve matching part are key parts in a hydraulic servo control product, wherein the throttling square hole of the valve sleeve part is required to ensure the requirements of axial position size and sharp edge and coplanarity, and the position and shape precision of the throttling square hole determine indexes such as precision of hydraulic flow output signals and logic conversion control. Because the square hole size is less, can't pass through contact measurement, the current valve barrel throttle square hole detects, adopts universal tool microscope to measure, needs artifical adjustment eyepiece, objective to focus, and measurement of inefficiency, the human factor influence is very big. According to the visual detection method for the valve sleeve throttling square hole, the three-coordinate and visual measurement are combined, the requirements on the size, the sharp edge and the coplanarity of the valve sleeve throttling square hole can be quickly and accurately measured, the measurement result is stable, and the influence of human factors is avoided.
Disclosure of Invention
The purpose of the invention is: the detection method for the throttling square hole of the valve sleeve can visually, quickly and accurately measure the size, the sharp edge and the coplanarity requirement of the throttling square hole of the valve sleeve, and is stable in measurement result and free from influence of human factors.
The technical scheme of the invention is as follows:
the method for visually detecting the throttling square hole of the valve sleeve utilizes a three-coordinate measuring machine and an image measuring head and is characterized by comprising the following steps of:
the method comprises the following steps: clamping and fixing the valve sleeve, and positioning the center of the valve sleeve throttling square hole and the plane of the valve sleeve throttling square hole orifice by utilizing a three-coordinate measuring probe to obtain spatial position data of the center of the valve sleeve throttling square hole and the plane of the valve sleeve throttling square hole orifice; replacing a measuring needle of the three-coordinate measuring machine with an image measuring head, and acquiring an orifice image of a throttle square hole of the valve sleeve through the image measuring head;
step two: denoising the orifice image, and then performing binarization processing to obtain a binarized orifice image;
step three, acquiring orifice boundary points of the throttling square hole from the binarized orifice image, and fitting a rectangular boundary line and the length and width of the rectangle through the acquired orifice boundary points;
step four: the four rectangular boundary lines are parallelly offset to the center of the rectangle by the same distance to obtain four offset boundary lines, the offset boundary lines are intersected to obtain four intersection points which are used as reference points
And fifthly, intercepting the orifice boundary points in the binary orifice image through the reference point and two offset boundary lines passing through the reference point, and judging whether the distance between each intercepted orifice boundary point and the reference point meets a preset value or not.
Further, under the condition that a plurality of valve sleeve throttling square holes are annularly arranged on the valve sleeves, after the center of one valve sleeve throttling square hole and the plane where the orifice of the valve sleeve throttling square hole is located are positioned in the step one, the image measuring head is rotated, the orifice of each valve sleeve throttling square hole is subjected to image acquisition, all the orifice images are compared, and whether the horizontal positions of all the valve sleeve throttling square holes meet the process standard or not is judged.
Further, the same distance is 0.05mm or less. For example 0.03 mm.
Further, in the denoising processing in the second step, a method of subtracting the images which are polished and not polished at the same position is adopted to remove the non-random noise in the images, and the images with the non-random noise removed are obtained;
and denoising the image without the non-random noise by adopting a Gaussian denoising method, and removing the random noise in the image, thereby obtaining the square hole image without the random noise.
Further, selecting a threshold value according to the gray level histogram of the orifice image, and performing binarization processing on the orifice image according to the selected threshold value;
further, in the third step, four boundary lines are fitted by the orifice boundary points of the orifice square hole corresponding to each side of the orifice, and the average distance between a pair of the boundary lines at the opposite positions is obtained.
Further, in the fifth step, whether the distance between each intercepted orifice boundary point and the reference point is greater than or equal to 0.05mm is judged.
And if the distances are all larger than or equal to 0.05, the requirement of R0.05max is met, and otherwise, the requirement of R0.05max is not met.
When the measuring head is influenced by rotation, the measuring head can rotate 90 degrees or 180 degrees every time, the size of the relative throttling square holes is detected by the same method, the average distance between the boundary point on the two relative square holes and the reference surface of the valve sleeve is respectively calculated, if the average distance difference is less than or equal to 0.005, the requirement of coplanarity 0.005 is met, otherwise, the requirement of coplanarity 0.005 is not met.
The invention has the advantages that: the method of the invention combines three-coordinate measurement and vision measurement, can quickly and accurately measure the size, the sharp edge and the coplanarity requirement of the throttling square hole of the valve sleeve, has stable measurement result and is not influenced by human factors.
Drawings
FIG. 1 is a schematic view of the measurement of the throttling square hole sharp edge R0.05max of the invention;
FIG. 2 is an image of a square orifice of the inventive throttle;
Detailed Description
The invention is described in further detail below with reference to the figures and the detailed description.
In the present example, the measurement accuracy of the three coordinates was (1.69+ L/280) μm, and the resolution of the visual measurement was 2.5 μm.
A valve sleeve throttling square hole visual detection method comprises the following steps:
the method comprises the following steps: calibrating a measuring system by adopting a three-coordinate measuring head, and acquiring a square hole image of the throttling square hole of the valve sleeve by utilizing a visual image measuring head;
step two: denoising the acquired square hole image to obtain a denoised square hole image, which comprises the following substeps:
step 2.1: removing non-random noise in the image by adopting a method of subtracting the polished square hole image and the non-polished image at the same position to obtain an image with the non-random noise removed;
step 2.2: and denoising the image without the non-random noise by adopting a Gaussian denoising method, and removing the random noise in the image, thereby obtaining the square hole image without the random noise.
Step three: the method comprises the following steps of carrying out binarization processing on a square hole image, obtaining boundary points of the throttling square hole, fitting the boundary line, and obtaining the length and width of the throttling square hole of the valve sleeve, and comprises the following substeps:
step 3.1: selecting a proper threshold value according to the gray level histogram of the square hole image, carrying out binarization processing on the square hole image, and identifying a gray level catastrophe point and extracting a square hole boundary according to the binarized image;
step 3.2: fitting two long boundary lines of the square hole, calculating the average distance from each long boundary point to the opposite long boundary line, namely the size in the length direction of the square hole, fitting two wide boundary lines of the square hole, and calculating the average distance from each wide boundary point to the opposite wide boundary line, namely the size in the width direction of the square hole.
Step four: and (3) offsetting the boundary line, and judging whether the four corners of the throttling square hole meet R0.05max, wherein the specific method comprises the following steps:
and respectively offsetting the four boundary lines of the square hole to the center of the square hole by 0.05 to obtain 4 intersection points, respectively calculating the distance from the boundary point within the range of 90 degrees of the four corners to the nearest intersection point, and if the distances are more than or equal to 0.05, meeting the requirement of R0.05max, otherwise, not meeting the requirement of R0.05max.
Step five: rotating the measuring head, detecting the size of the relative throttling square hole, and judging whether the coplanarity of the throttling square hole meets the requirement of 0.005 or not, wherein the specific method comprises the following steps:
rotating the measuring head by 180 degrees, detecting the sizes of the relative throttling square holes by the same method, respectively calculating the average distance between the boundary points of the two relative square holes and the reference surface of the valve sleeve, if the average distance difference is less than or equal to 0.005, the requirement of coplanarity degree of 0.005 is met, otherwise, the requirement of coplanarity degree of 0.005 is not met.
Claims (8)
1. A valve sleeve throttling square hole visual detection method utilizes a three-coordinate measuring machine and an image measuring head, and is characterized by comprising the following steps:
the method comprises the following steps: clamping and fixing the valve sleeve, and positioning the center of the valve sleeve throttling square hole and the plane of the valve sleeve throttling square hole orifice by utilizing a three-coordinate measuring probe to obtain spatial position data of the center of the valve sleeve throttling square hole and the plane of the valve sleeve throttling square hole orifice; replacing a measuring needle of the three-coordinate measuring machine with an image measuring head, and acquiring an orifice image of a throttle square hole of the valve sleeve through the image measuring head;
step two: denoising the orifice image, and then performing binarization processing to obtain a binarized orifice image;
step three, acquiring orifice boundary points of the throttling square hole from the binarized orifice image, and fitting a rectangular boundary line and the length and width of the rectangle through the acquired orifice boundary points;
step four: the four rectangular boundary lines are parallelly offset to the center of the rectangle by the same distance to obtain four offset boundary lines, the offset boundary lines are intersected to obtain four intersection points which are used as reference points
And fifthly, intercepting the orifice boundary points in the binary orifice image through the reference point and two offset boundary lines passing through the reference point, and judging whether the distance between each intercepted orifice boundary point and the reference point meets a preset value or not.
2. The visual detection method for the throttle square hole of the valve sleeve as claimed in claim 1, wherein: and under the condition that a plurality of valve sleeve throttling square holes are annularly arranged on the valve sleeve, after the plane where the center of one valve sleeve throttling square hole and the orifice of the valve sleeve throttling square hole are located is positioned in the step one, the image measuring head is rotated, the image of each valve sleeve throttling square hole orifice is obtained, all orifice images are compared, and whether the horizontal positions of all the valve sleeve throttling square holes meet the process standard or not is judged.
3. The visual detection method for the throttle square hole of the valve sleeve as claimed in claim 1, wherein: the same distance is 0.05mm or less.
4. The visual detection method for the throttle square hole of the valve sleeve as claimed in claim 1, wherein: in the denoising treatment in the second step, the non-random noise in the image is removed by adopting a method of subtracting the images which are polished and not polished at the same position, and the image without the non-random noise is obtained;
and denoising the image without the non-random noise by adopting a Gaussian denoising method, and removing the random noise in the image, thereby obtaining the square hole image without the random noise.
5. The visual detection method for the throttle square hole of the valve sleeve as claimed in claim 1, wherein: and selecting a threshold value according to the gray level histogram of the aperture image, and performing binarization processing on the aperture image according to the selected threshold value.
6. The visual detection method for the throttle square hole of the valve sleeve as claimed in claim 1, wherein: in the third step, four boundary lines are fitted through the orifice boundary points of the throttling square holes corresponding to each side of the orifice, and the average distance between a pair of the boundary lines at opposite positions is obtained.
7. The visual detection method for the throttle square hole of the valve sleeve as claimed in claim 1, wherein: and step five, judging whether the distance between each intercepted orifice boundary point and the reference point is greater than or equal to 0.05 mm.
8. The visual detection method for the throttle square hole of the valve sleeve as claimed in claim 1, wherein: the same distance is 0.03 mm.
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| CN202011444969.XA CN112529869B (en) | 2020-12-11 | 2020-12-11 | Valve sleeve throttling square hole detection method |
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| CN202011444969.XA CN112529869B (en) | 2020-12-11 | 2020-12-11 | Valve sleeve throttling square hole detection method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114739314A (en) * | 2022-03-01 | 2022-07-12 | 上海交通大学 | Method and device for precisely measuring profile of square hole of valve sleeve shell of electro-hydraulic servo valve |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114739314A (en) * | 2022-03-01 | 2022-07-12 | 上海交通大学 | Method and device for precisely measuring profile of square hole of valve sleeve shell of electro-hydraulic servo valve |
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