A kind of tubing round thread dimensional parameters detection method and equipment
The invention belongs to machine components detection technique field, relate to digital picture acquisition methods and the equipment of part, can be used for regular screw threads and the detection of other accessory sizes.
Oil pipe is the pipeline that former oil and gas has transported from oil-gas Layer earth's surface after having drilled, and makes consumption very big in oil field, and the quality of tubing round thread directly influences the normal production in oil field.But at present in the production process of oil pipe, manual method is commonly used in tubing round thread dimensional measurement, using external thread gauge and cone gauge to coordinate a series of instruments to carry out manual detection, this measuring method inefficiency, artifical influence factor is very big.
How quickly, accurately measure the size of tubing round thread spatial geometric shape, be a current detection technology difficult problem urgently to be resolved hurrily.
Universal threaded measuring instrument is divided into contact and optical laying formula.Contact type measurement instrument realizes the measurement of screw thread by two hemispherics self-centering methods of probe, there is problems of the processing request to probe high, probe easily abrasion in use procedure, probe easily comes off, needing when measuring screw thread to use the supplementary meanss such as three pins, efficiency is low, complex operation.Optical laying formula is mainly through optical instrument measurements such as universal tool-measuring microscopes, and the subject matter existed is by human eye visual sight, and personal error factor is many, automaticity is low, efficiency is low, and long-time use causes people eyestrain, and universal threaded measuring instrument can not on-line measurement.
Summary of the invention
Present invention aims to the deficiency that above-mentioned existing detection method exists, it is proposed to the method and apparatus of a kind of image on-line checking tubing round thread physical dimension, to improve detection efficiency, accuracy of detection, reduce detection equipment cost.
In order to realize foregoing invention purpose, adopt following detection method:
1, use parallel LED illumination light source, doubly telecentric camera lens, area array CCD digital monochrome collected by camera thread segment image；
2, extract profile sub-pixel edge with image processing software；
3, calculate threads geometrical parameters, the parameter such as including the tooth depth of screw thread, pitch, cone angle and diameter.
The detection equipment of the present invention:
Technical scheme: main be made up of base and the image acquisition component that is arranged on base, image acquisition component by the bracket being arranged on base, be fixed on bracket two restraint parallel LED illumination light source, two doubly telecentric camera lenses, two area array CCD digital monochrome cameras and image acquisition and process software forms.
In image acquisition component, parallel LED illumination light source and telecentric lens are coaxially mounted on bracket.Bracket is arranged on base, it is desirable to lens axis is parallel with light source axis, is positioned at screw thread tooth depth part.
Top image acquisition component is arranged on support plate rail plate, and this rail plate is provided with the elevating screw being mated lifting, and tested tubing round thread is placed on processing unit (plant) support, and measurement apparatus camera lens is parallel with hand of thread spiral.
The source of parallel light of described two groups of doubly telecentric camera lenses and correspondence；Upper group of camera lens light source can according to tubing diameter up-down adjustment position；It is connected with camera lens light source bracket.
Image acquisition and the isoparametric calculating process of tooth depth, pitch, cone angle and diameter:
Adjust base, adjust lens location by base, make lens axis be positioned at thread segment immediate vicinity, fix camera position.
Illumination intensity, camera gain and aperture time are set.
The uncalibrated image of shooting known fixed size component, comes the position of calibration for cameras.Uncalibrated image is made up of two, top and the bottom image, and this group image is detected edge line, and under present image coordinate system, two straight lines of setpoint distance edge line half diametral distance are as demarcation.
Gather screw thread gray level image to be measured with camera real-time online, and the measurement image in gatherer process can be intercepted at any time.
With image processing software the screw image intercepted is processed, computing, obtain corresponding geometric parameter, the parameter such as the tooth depth of screw thread, pitch, cone angle and diameter.
Detection method simple in construction, installation cost is low, simple to operate, and error is in 0.003mm.
Beneficial effects of the present invention:
Part parts physical dimension measurement will be offered convenience and measure more accurately by the present invention, is convenient for measuring, and is also more conducive to the accurate processing of machine part.
The major advantage of the present invention:
Adopting source of parallel light, telecentric lens can ensure that the External Shape image collected, and is not distorted with distance within the specific limits.Software measurement image parameter speed is fast.
Image procossing adopts sub-pix calculate, obtain the measurement result of degree of precision.
May be mounted on process equipment, On-line sampling system.
Accompanying drawing explanation
In order to be illustrated more clearly that embodiment of the present invention technical scheme, below the accompanying drawing used required during embodiment is described is briefly described, apparently, accompanying drawing in the following describes is only that the present invention is in order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below the accompanying drawing used required in p-embodiment or description of the prior art is briefly described, for those of ordinary skill in the art, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the structural representation of the present invention.
In figure: 1, base, 2, CCD digital monochrome cameras, 3, doubly telecentric camera lens, 4, camera lens light source bracket, 5, rail plate, 6, support riser, 7, elevating screw, 8, parallel LED illumination light source, 9, tested screw thread.
Detailed description of the invention
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is only a part of embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under not making creative work premise, broadly fall into the scope of protection of the invention.
Camera calibration is measured, known profile size component is installed on part processing stations to be measured, adjust correct position, make its lower edges fall within two camera perspectives, shoot its contour images, set camera gain and aperture time, gather image, obtain demarcating upper and lower two the cross section gray-scale image of parts, extract two width image border profiles, calibrate the position relationship between two cameras by contour line relevant position.
Screw thread physical dimension is measured: keep each asset location motionless placement screw thread to be measured, gather upper and lower two the interface gray level images of screw thread, extract thread contour edge in image, find the lower edges of thread, calculating the equation of upper edge and place, lower edge straight line, the distance between two straight lines is the tooth depth of screw thread；Finding out a parallel lines between two straight lines, there is intersection point at this straight line and helical gear edge, and the distance often skipping an intersection point is pitch；Utilize the silhouette edge extracted edge and utilize its cone angle of calibrated and calculated and diameter.Each parameter above, or use nominal data, each through geometrical calculation, obtain the physical dimension parameter of thread segment.
The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all within the spirit and principles in the present invention, any amendment of making, equivalent replacement, improvement etc., should be included within protection scope of the present invention.