GB2519692A - Combined ray non-destructive testing method and system - Google Patents
Combined ray non-destructive testing method and system Download PDFInfo
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- GB2519692A GB2519692A GB1501147.1A GB201501147A GB2519692A GB 2519692 A GB2519692 A GB 2519692A GB 201501147 A GB201501147 A GB 201501147A GB 2519692 A GB2519692 A GB 2519692A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/06—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption
- G01N23/083—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption the radiation being X-rays
- G01N23/087—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption the radiation being X-rays using polyenergetic X-rays
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Abstract
A combined ray non-destructive testing method and system. The method and the system integrate γ-ray source (13) and X-ray source (9) to a solid linear array detector (2), a gas linear array detector (4), and a plane array detector (6) on a rigid substrate (5) respectively with a ray source support (10) and a detector support (1). Through a combination of a different ray source and a different detector, DR scanning imaging and fault or cone-beam CT imaging are respectively performed, thereby implementing a multi-energy segment multi-mode combination high-precision ray non-destructive test on a workpiece, and meeting such test requirements as high detection resolution, high detection sensitivity, high ray penetration capability, and desirable long-term stability.
Description
I
Method and system for combined ray non-destructive testing
Field of the Invention
The present invention relates to a method and a system for combined ray non-destructive testing, and in particular to a method and a system for combined ray non-destructive testing which using y-ray source and X-ray source as well as linear array detectors and planar array detectors, which method and system may carry out high-precision DR (digital radiography)/CT (computed tomography) radiography testing on a workpiece in various ray source-detector combination manners. The present invention pertains to the technical field of ray non-destructive testing, and can be applied for sophisticated non-destructive testing in the fields of national defense, aerospace, industry, scientific researches and the like.
Background of the Invention
DR (digital radiography) and CT (computed tomography) techniques are common ray non-destructive testing technologies in medical and industrial fields. The existing ray non-destructive testing systems usually have single fUnction, and are mainly used for the testing of a certain type of workpieces or defects, most of their performance indicator such as contrast sensitivity, spatial resolution, penetrating power, long-term stability and the like are individually prominent and it is difficult to seek a balance between them.
Depending on the difference in the ray sources as used, ray non-destructive testing systems are divided into high-energy systems and mediwn&low-energy systems. In the high-energy systems, an X-ray accelerator is usually used as the ray source, and in the medium& low-energy systems, an X-ray machine or a radioactive isotope are usually used as the ray source. With regard to different ray sources, detection indicators such as applicative thickness range of tested workpiece, defect resolution are different as well due to differences in ray energy, intensity, fbcal spot size and output stability. On the other hand, there are also various detectors for radiation imaging, which differs in detection efficiency, detection sensitivity, pixel sizes, imaging speed, radiation resistance, and environmental adaptability, and the like.
Moreover, detection performance is closely related with the energy of incident ray, i.e. the signal response characteristics of detectors of the same type are also significantly different for X/7 rays having different energy range, and signal response characteristics which are not suitable for rays with a certain energy range may be ideal in case of rays with another energy range. However, the ray non-destructive testing systems disclosed in the prior arts have a common characteristic, that is, only one ray source and one detector are usually used, namely, only one of the X-ray machine, the X-ray accelerator and the 7-ray source are independently used, and only one of the planar array detector and the linear array detector are used, thus a plurality of energy range and high stability are difficult to be acquired simultaneously, the advantages of different types of detector are difficult to be frilly used, the defect resolving power is limited, and detection effect in a wide energy range is difficult to be achieved, The limitations and shortcomings are described in detail as follows.
1 The energy range of the ray is narrow, and objects suitable for testing are limited.
Generally speaking, the higher the ray energy is, the higher the penetrating power is.
However, higher ray energy does not necessarily bring higher detection accuracy. A rekitively low ray energy will result in an insufficient penetrating power; if the ray energy is too high, though the penetrating power will be enhanced, too few ray attenuation will cause decreasing in the contrast sensitivity of an imaging system and the imaging quality is thus influenced. For workpieces with different dimensions and defects with different dimensions in the workpieces, rays with different energies need to be used for testing, or, for rays of certain energy, there is an optimum thickness range for measurement, For example, the optimum testing thickness for a 450kV X-ray machine is about 2.3 cm equivalent iron thickness, the optimal testing thickness of a Co-60 7-ray source is about 4,7 cm equivalent iron thickness, and the optimal testing thickness of a 15 MeV X-ray accelerator is about 8 cm equivalent iron thickness, and the like. A testing system using different ray sources can acquire highest testing accuracy near the optimal testing thickness, and the testing effect is the best. The testing capacity is declined if the testing system deviates from this range.
Therefore, testing systems using a single ray source are limited by the ray energy range and have a narrow range for objects applicable for testing and a limited defect resolving power, which is also an important reason that industrial CT systems usually need to be customized on the basis of the tested objects.
2. The detection capacity cannot be furthest improved by comprehensively utilizing the advantages of different types of ray source Any one type of ray sources has its advantages as well as shortcomings in the case of being used for radiation imaging, particularly: (i) the ray source of the X-ray machine has a small focal spot size, high ray intensity and allows a quite high spatial resolution, but the ray is of low energy and has a continuous energy spectmm, causing the issues such as low capacity penetrating power and ray beam hardening. For workpieces with low mass thickness, a good testing effect is obtained, while for workpieces having relatively high mass thickness and subj ect to stringent stability requirements, the requirements for which the dimensions of defects needs fine quantitative testing is difficult to meet; (ii) the ray of the X-ray accelerator has high energy and high intensity and can penetrate through thick workpieces, but it has a large focal spot, substantially distinct spatial distributions of ray intensity and energy, strong beam-forward, poor X-ray output stability. Also the problem of ray beam hardening exists as its energy spectrum is continuous. Although the workpieces with large mass thicknesses can be tested, the spatial resolution, testing sensitivity, measurement stability and the like are all limited, In addition, due to the small X-ray beam field angle of the accelerator, the space occupied by the testing system is large if workpieces with large dimensions need to be tested, the mechanical structure is also complicated, and the radiation protection requirements are also high; (iii) with regard to a y-ray source, for example, Co-GO, its ray intensity gradually weakens on a fixed half-life basis and may be determined and calculable at any time, The spatial distribution of its intensity is isotropic, and the generated y-rays are single-energy y-rays of 1. 17 MeV and 1.33 MeY, The problem of ray hardening substarnially does not exist, and the y-ray source has a strong penetrating power comparable to that of a 4 MeV accelerator and is especially suitable for testing minor changes in the mass thicknesses of the workpiece over a long period of time, but the shortcomings that the ray has large target dimensions source and ow ray intensity is still present. Any of these types of ray source has the limitations if used independently, and if these types of ray sources are used in combination, particularly, the 7-ray source, for example, Co-60, is used in combination with the X-ray machine, their respective shortcomings can be made up for each other, thus a maximum efficacy can be achieved for the combined testing system.
3. The advantages of the various detectors cannot be frilly taken and the testing capacity cannot be improved to a greatest extent.
Different types of detectors have different characteristics, each has advantages and limitations, particularly (i) planar array detector: the spatial resolution is high and may be up to a p.m level, and the imaging speed is high, but the thickness of a sensitive body is only 0.2-0.5mm, the detection efficiency is low, secondary electron crosstalk is difficult to eliminate, and thus the planar array detector is suitable for testing low-energy rays; (ii) a solid linear array detector: the thickness of a sensitive body may be up to a cm level, the detection efficiency is high, and the testing sensitivity is high, but the spatial resolution is difficult to be up to a I.tm level, line-by-line scanning is needed, the imaging speed is slow, and the solid linear array detector is easily influenced by radiation, environmental temperature and humidity and other factors, and poor in long-term stability; (iii) a gas linear array detector: the performance is stable, the environmental adaptability is high, radiation can be resisted, but it is difficult to make the dimensions of detector units small, and the spatial resolution is greatly limited. Therefore, with regard to different ray energies and different defects, the optimum testing effect can be acquired only by using different types of detectors, and it is difficult for a single type of detectors to be qualified for complex testing requirements.
4. The testing needs for high sensitivity, high peneirating power and good long-term stability cannot be met simultaneously.
In some special fields, the tested objects have relatively large mass thicknesses (equivalent to several centimeters of iron), and need quite high requirement for testing accuracy, so it is required to identi1 defects of tiny cracks (at a pm level)), scaling, bubbling and the like, and to find a small change of 0.1% in the mass thickness and the like occurring within a long period of time (several months to even years). In this case, requirements for the indexes of spatial resolution, testing sensitivity, long-term stability and the like are high, and it is difficult to be realized by the existing radiation imaging testing systems.
Summary of the Invention
The technical problem to be solved by the present invention is to overcome the shortcomings of use of a single ray source and single detector working mode of the existing radiation imaging testing system, and to realize a combined multi-energy range and multi-mode testing on workpieces in one integrated miniaturized system, so as to meet the testing requirements of high testing resolution, high detection sensitivity, high ray penetrating power, good long-term stability and the like.
In order to solve the technical problem above, the present invention discloses a combined ray non-destructive testing method, and a combined ray non-destructive testing system using the method. According to the method and the system, a multi-energy range and multi-mode DR/CT ray non-destructive testing with high resolution, high accuracy and high stability is realized on the combined ray non-destructive testing system comprising a y-ray source, an X-ray source, a linear array detector and a planar array detector is realized through various combinations of different ray sources and different detectors.
The combined ray non-destructive testing method disclosed by the present invention is particularly as follows. Workpieces are irradiated by the X-ray or y-ray generated by a ray source, the rays penetrating through the workpieces are received by a detector and converted to digital signals, and then the radiation images of the workpieces are acquired through processing the signals, wherein a combined ray source comprising an X-ray source and a 7-ray source is used as the ray source, combined detectors comprising a solid linear array detector, a gas linear array detector and a planar array detector is used as the detector, and DR scanning imaging or slice CT imaging or cone-beam CT imaging for the workpiece is realized by switching among different ray sources and testing units comprising different detectors; and the combined ray source, the combined detectors, and a workpiece rotating table are all installed on a same rigid base.
Further, a front collimator is arranged at the ray outlet of the combined ray source, the front collimator is used for collimating the rays into fan-shaped beams or cone-shaped beams, and a rear collimator is arranged at the ray inlet of the combined detector; when the switched-on detector is a solid linear array detector or a gas linear array detector, the rear collimator is used for collimating the rays into small ray beams having comparable height and number with the detector unit, and the width of the collimating slit of the rear collimator is smaller than the width of the detector unit; during DR imaging, the rear collimator is capable of creeping along the width direction of the detector unit, and one set of projection data is acquired for each creep of the rear collimator, and the distance of each creep is the width of the collimating slit.
A combined ray non-destructive testing system using the method above, comprising: a rigid base on which a ray source support, a workpiece rotating table and a detector support are sequentially arranged at intervals; the ray source support is provided with a combined ray source comprising a y-ray source and an X-ray source, a switching mechanism for displacing different ray sources in the combined ray source to working positions, and a mechanism for allowing the displaced detectors up-and-down, front-and-back, left-and-right, and rotating operations; the detector support is provided with a combined detector comprising a solid linear array detector, a gas linear array detector and a planar array detector, a switching mechanism used for displacing different detectors in the combined detector to working positions, and a mechanism used for allowing the displaced detectors up-and-down, front-and-back, left-and-right and rotation operations; the ray source support is provided with a front collimator capable of collimating the rays emitted by the ray sources into fan-shaped beams or cone-shaped beams, and the detector support is provided with a rear coflimator used for carrying out further collimation processing on the rays; the gas linear array detector and the solid linear array detector are both of an arc-shaped structure, after the gas linear array detector and the solid linear array detector are shifted in the working position, the ray incidence windows of various detector units in the detector are uniformly and closely arranged along a circular arc taking the source centre of the ray source in the working position as the centre of circle through which the central line of each detector unit passes, each rear collimator matching the gas linear array detector or the solid linear array detector is also of an arc-shaped structure taking the source centre of the ray source in the working position as the circle centre, the collimating slit of the rear collimator is capable of collimating the fan-shaped ray beams into small ray beams which are in one-by-one correspondence with individual detector units of the detector, and the width of collimating slit is smaller than the width of the detector unit; during DR imaging, the rear collimator is closely adjacent to the gas linear array detector or the solid linear array detector, and may creep in direction of arrangement of the detector units, and the distance for each creep is the width of the collimating slit.
Further, the width of each collimating slit is 1/2 or 1/3 or 1/4 of the width of the detector unit. a
Further, the 7-ray source is a Co-6O or Cs-137 or Ir-192 radioisotope 7-ray source.
Further, the X-ray source is a small focal spot X-ray machine, a micro-focus X-ray machine and/or an X-ray accelerator.
Further, the planar array detector is an amorphous silicon planar array detector, an amorphous selenium planar array detector or a CMOS planar array detector.
Further, the gas linear array detector is a gas-filled ionization chamber linear array detector or a multi-wire proportional chamber linear array detector or a Geiger counting tube linear array detector.
Further, the solid linear array detector is a solid scintillator linear array detector or a semiconductor linear array detector.
Further, the scintillator of the solid scintillator linear array detector is NaI,CsI, CdWO4, LaBr3, orLaCl3, It has been proved in practice that the multi-energy range, multi-mode and high-resolution combined ray non-destructive testing method and system of the present invention have a good testing effect on the tested workpieces and the defects therein, and quite high spatial resolution and density resolution may be obtained, and the testing of small changes in mass thickness in the interior areas of interest of the workpieces over a long period of time.
The testing system of the present invention provides a wide range of ray source energy which may comprise medium-& high-energy y-ray sources (ray energy ranging from several hundreds of key to several thousands of key) and may comprise medium-& low-energy X-ray sources (ray energy ranging from dozens of key to several hundreds of key), The method and the system of the present invention may comprehensively utilize the advantages of a plurality of energy ranges and rays of different attributes and are suitable for detecting workpieces having wider mass thickness range, and stronger firnctions may be realized and a higher testing capacity is achieved; different ray sources are combined with the planar array detector, the gas linear array detector or the solid linear array detector respectively to form different ray source-detector detection units, thus thst three-dimensional cone-beam CT stereo-imaging detection testing with different resolutions may be carded out, two-dimensional scanning DR or two-dimensional tomographic CT fine non-destructive testing may also be carried out in key areas, and thus the advantages of the various imaging detectors are hilly played; different types of ray sources and different types of detectors are combined into one system through an ingenious structural design, in which a single one device may provide several to dozens of ray source-detector combination modes, which is equivalent to several different types of testing systems, thus achieving a higher object adaptability, giving thU play to the characteristics of the different types of ray sources and the different types of detectors, and achieving a higher detectability for defects. The testing system of the present invention has compact structure, small size, smaller floor area, high adaptability for thicknesses, shapes and dimensions of the workpieces, provides high accuracy of defect testing, powerful functions, high cost performance, and is especially suitable for application places with significant differences in tested object and strigent testing requirements, thus various high-accuracy and complicated testing requirements in sectors such as national defense, aerospace, industry, scientific researches and etc can be met.
Brief Description of the Drawings
Fig. 1 is a perspective diagram of the combined ray non-destructive testing system of the present invention.
Fig. 2 shows the structures of the detector units of linear array detectors and the collimating slits of the rear collimator, and the partially enlarged creeping direction of the rear collimators.
Fig. 3 is a side sectional view of the y-ray source.
Detailed Description of the Embodiments
The specific embodiments of the present invention are described below in detail by referring to the accompanying drawings.
As shown in Fig. t, the combined ray non-destructive testing system of the present invention comprises: a base 5 and iron pad 14 at the bottom thereoQ a ray source support 10 and a detector support 1 perpendicularly fixed on the base; a ray source rack 12 liftable or translatable and positionable along the ray source support 10; a detector rack 7 liftable or translatable and positionable along the detector support I; an X-ray source 9 and a y-ray source 13 mounted on the ray source rack 12; a planar array detector 6, a solid linear array detector 2 and a gas linear array detector 4 fixed on the detector rack 7; a workpiece rotating table t S and a workpiece clamp 8 thereon; and a front collimator it for ray sources and a rear collimator 3 for the linear array detectors.
The workpiece rotating table 15 is rotable and liftable or translatable in a direction parallel or perpendicular to the connection line between the ray source and the detector. The ray source and the detector may be lifted or translated together with their respective racks, and may be accurately positioned in a specified position. The ray outlets for X-ray source 9 and y-ray source 13 are respectively provided with a front collimator ii which is made of a lead alloy material, a tungsten alloy material, or a depleted uranium material, and a horizontal horn-shaped slit and square-cone-shaped holes are formed internally the front collimator and may be switched through horizontal displacement so as to collimate rays into fan-shaped beams or square-cone-shaped beams for imaging of the linear array detector or the planar array detector respectively. Installed respectively at the ray inlet side of the solid linear aray detector 2 and the gas linear array detector 4 is a rear collimator 3 for further collimating the fan-shaped rays which are about to enter the linear array detectors into a plurality of small ray beams corresponding to the detector units. The box-shaped areas outside the active areas (that is, square areas formed by sensitive materials for detecting X-rays or y-rays) of the planar array detector 6 are covered by a lead alloy or tungsten alloy fiat shielding material (not shown in Fig. 1), so as to prevent the electronic components of the planar array detector 6 from radiation damages caused by the rays. The base 5 is made of an integral cast iron, stone or steel-structure frame, plays the roles of rigid supporting and damping, and serves as a reference plane for installation and adjustment of the whole testing system. The iron pad 14 is used for adjusting the base 5 to a horizontal state, a number of 4, 6 or 8 iron pads 14 are generally provided and distributed at four corners of the lower surface of the base 5 or in the middle position of the four sides.
The testing system of the present invention comprises a planar array detector and a linear array detector, both of which may be combined with the X-ray source or the y-ray source respectively so as to carry out DR imaging and CT imaging, and the (1) DR imaging of the planar array detector: a s&ected ray source and the planar array detector are lifted or translated to a set position, so that the centre of the ray source and the centre of the planar array detector are in a same horizontal plane, and the workpiece is completely contained in the imaging area of the planar array detector; the front collimator is horizontally displaced to the position of cone-shaped hole, the shutter of the ray source is opened, and the rays are collimated by the front collimator 11 into cone-shaped beams, penetrate through the workpieces and subsequently are received by the planar array detector 6, so as to acquire two-dimensional DR projection images.
(2) CT imaging of the planar array detector: a selected ray source and the planar array detector are lifted or translated to set positions, so that the centre of the ray source and the centre of the p'anar array detector are positioned in same horizontal plane, and the workpiece is completely contained in the imaging area of the planar array detector; the front collimator is horizontally displaced to the position of cone-shaped hole, the shutter of the ray source is opened, the workpiece rotating table is rotated by 360 degrees at a set rotational speed, one frame of projection image is acquired for each rotational step, and after acquisition of all projection data is completed, the three-dimensional cone-beam CT images of the worlcpiece are acquired through data processing and image reconstmction.
The DR imaging of the linear array detector may be realized in two scanning modes.
1) The selected ray source and the linear array detector are lifted or translated to a set position, so that the centre of the ray source and the centre of the linear array detector are positioned in a same horizontal plane (a testing plane), and the testing plane is slightly higher than the top end of the workpiece or slightly lower than the bottom end of the workpiece (outside the testing area), the front collimator is displaced to the positions of the slit, the shutter of the ray source is opened, the rotating table 15 supports the tested workpiece to allow the tested workpiece to ascend or descend at a set constant speed, the sheet-shaped ray beams collimated by the front collimator ii are used for perpendicularly scanning the tested workpiece. The rays penetrating through the workpiece are received by the solid linear array detector 2 or the gas linear array detector 4 after being collimated by the rear collimator 3 and converted to DR projection images by a data processing system.
2) The selected ray source and the linear array detectors are lifted or translated to set positions, so that the centre of the ray source and the centre of the linear array detector are positioned in the same horizontal plane (the testing plane), and the testing plane is slightly higher than the top end of the workpiece or slightly lower than the bottom end of the workpiece (outside testing areas), the front collimator is displaced to the position of the slit, the shutter of the ray source is opened, the ray sources and the linear array detectors synchronously descend or ascend at a set constant speed, the sheet-shaped ray beams coflimated by the front collimator 11 are used for perpendicularly scanning the tested workpiece, the rays penetrating through the workpiece are received by the solid linear array detector 2 or the gas linear array detector 4 after being collimated by the rear collimator 3 and converted to DR projection images by a data processing system.
As shown in Fig. 2, the gas linear array detector or the solid linear array detector is of an arc-shaped structure, and composed of a plurality of detector unit 21. The end surface of the detector unit 21 (that is, ray incidence windows), which faces the ray sources, are uniformly and closely aranged along a first arc line 24 which takes the source center of the ray source (that is, the target center of the X-ray source, or the radioactive source of the 7-ray source) as a circle centre, and takes the distance from the ray incidence window to the source center of the ray source as a radius. The height and the width of the detector unit 21 refer to the height and the width of the ray incidence window, and the product of the width and the height is the pixel value of the linear array detector, The number of the detector unit 21 should be such that the fan-shaped area formed by the length of the first arc line 24 defined by the ray incidence windows and the source center of the ray sources can cover each section needed to be tested for the tested workpiece, and preferably is the integer multiples of 8, The width of the ray incidence window of each detector unit 21 along the arc should meet the requirements for the testing resolution of the testing system of the present invention. The central line in the length direction of each detector unit 21 ((that is, a direction parallel to the rays) points to the source center of the ray source, The rear collimator 3 of the linear aray detector is also of an arc structure, a second arc line 25 of the rear collimator also takes the source center of the ray source as a circle centre, and the radius thereof is slightly smaller than that of the first arc line 24, The rear collimator 3 is composed of isolation sheets 23 which are uniformly arranged in parallel along the second arc line 25 and made of rectangular tungsten alloy sheets, and two (upper and lower) parallel clamping plates (not shown in Fig, 2) used for accurately fixing the isolation sheets 23 and made of red copper or lead alloy or tungsten alloy. A plurality of collimating slits 22 are formed between the isolation sheets 23 and the clamping plates, and used for further collimating the rays before entering the detectors into a plurality of small ray beams, The height of the collimating slit 22 is equal to the distance between two clamping plates, and the width is equal to the distance between two adjacent isolation sheets 23. The height of the collimating slit 22 is equal to or slightly greater than that of the detector unit 21, the width is 1/2 or 1/3 or 1/4 of the width of the detector unit 21, and the number of the collimating slit is equal to that of the detector unit 21. The extension line in the length direction (that is, the direction parallel to the rays) of the isolation sheet 23 passes through the source center of the ray source such that the central line of the collimating slit 22 also passes through the source center of the ray source, thus increasing efficiency of transmitting rays entering the detector units after passing through the collimating slits, blocking the scattering rays effectively, and reducing signal crosstalk between adjacent detector units 21. During the DR imaging of the linear array detectors, the rear collimator 3 is adapted to bidirectionally creep as a whole along the second arc line 25, a set of projection data is acquired for each creep of the rear collimator 3, and the distance for each creep is the width of the collimating slit 22, and then the spatial resolution of the DR imaging reaches 1/2 or 1/3 or 1/4 of the width of the detector unit 21, and the testing resolution of the testing system of the present invention may be further improved.
CT imaging of the linear array detectors: the selected ray source and the linear array detector are lifted or translated to set positions, so that the centre of the ray source and the centre of the linear array detector are positioned in a same horizontal plane (the testing plane), the workpiece rotating table 5 is lifted to a set position, and the portion to be tested of the workpiece is positioned in the testing plane; the front collimator is horizontally displaced to the position of cone-shaped hole, the ray source is opened, the workpiece rotating table 15 rotates by 360 degrees at a set rotational speed, a set of projection data is acquired when the workpiece rotating table 15 rotates by a constant angle. All of the data are subjected to data processing and image reconstruction after date acquisition is completed to give CT tomographic images of the tested portion of the worlcpiece.
As shown in Fig. 3, the y-ray source comprises: a shielding body 36 made of lead alloy or tungsten alloy or depleted uranium, in which a ray inlet 37 and a ray outlet 38 are provided; a rotary shutter 35 which is in the shielding body 36 and rotatable relative to the shielding body and provided with a horizontally-arranged rotation axis, in which shielding body a connection channel 39 adapted to selectively connects or disconnects the ray inlet 37 and the ray outlet 38 in the shielding body 36 when rotation takes places in the shielding body, the connection channel 39 expands in a shape of a horn from the ray inlet 37 to the ray outlet 38, forming ray channel expanding in horn-shape together with the ray inlet 37 and the ray outlet 38 of the shielding body 36, such that the y-rays are in the form of flit-shaped beams or cone-shaped beams; and a radioactive source 34 positioned at the initial position of the ray inlet 37.
The 7-ray source comprising the shielding body 36 and the horizontally-arranged rotary shutter 35 is used, wherein the rotary shutter is provided with a connection channel 39 expanding in a horn-shape in the rotary shutter 35. Since the gravity centre of the rotary shutter 35 deviates from the rotation axis thereof such that the rotary shutter 35 may be rotated by virtue of its own gravity in case where no external force is exerted, thus interrupting the rays, providing the y-ray source with an inherent safety performance of automatically turning off the rays in case of power-off According to the present invention, the X-ray source and the y-ray source are integrated into an integrated miniaturized testing system. By lifting or translational displacement of the ray sources and the detectors, different my sources and different detectors may be combined in pair to form dozens of testing modes. And different testing modes are suitable for testing defects of different objects, different types and dimensions, so as to meet different testing requirements. Take the combination of a 450kV X-ray machine and a Co-60 y-ray source as an example, the 450kV X-ray machine has small target (up to 0.4 mm), high radiation intensity (a dosage rate at a distance I m away from the target is up to hundreds of mGy/min), and a quite high spatial resolution (for example, up to 4.4 lp/mm by being matched with the planar array detector) can be achieved for workpieces with an equivalent mass thicknesses smaller than 60mm iron; the Co-60 y-ray source has high energy (an average energy of 1.25Mev), its ray penetrating power which is equivalent to that of a 4MeV accelerator, and it is suitable for testing workpieces with equivalent mass thicknesses of 30-130 mm iron, achieving a density resolution of as high as 0.1%. By using the characteristic of stable ray output intensity of the 7-ray source, the distance between any two points in the workpiece may also be measured, and small changes in the mass thicknesses of any interior local area of the workpieces over a long period of time may also be detected. If a micro-focus X-ray machine is selected, the testing resolution of the system may be further improved to an order of several microns.
Embodiment I In the embodiment, two ray sources, i.e. a Co-60 y-ray source and a 4SOkeV small focus X-ray machine are adopted, and a planar array detector, a scintillator solid linear array detector and a gas-filled ionization chamber gas linear array detector are used as detectors. The activity of the Co-60 ray source as used is about 3.7TBq (100 Curies), the focus size of the 45OkeV X-ray machine is 0.4mm, and the maximum tube current is 3.3mA. The dimensions of imaging area of the planar array detector are 409.6x409,6mm2, the pixel dimensions are 0.2x0,2mm2; in the solid linear array detector, a CdWO4 crystal is used as a scintillator, and the pixel dimensions are 0,4x5x30mm3, In the gas linear array detector, a gas-tilled ionization chamber is adopted, xenon is taken as a working medium, and the gas-tilling pressure is 3.SMPa.
The shielding container for the y-ray source, the front collimator and the rear collimator are all made of tungsten alloy having a density of greater than 18g/cm3.
The lifting or translation of the ray source rack and the detector rack, and the lifting or bidirectional translation of the workpiece rotating table are realized by a linear guide rail and a servo motor, position measurements are realized by a rotary encoder and a grating scale, and the repeatitive positioning precison is lower than lOjim; the minimum rotation step length of the workpiece rotating table is 15', and the repeatitive positioning accuracy is less than 2". The overall dimensions of the whole testing system are 2.Smx I.8mx2.2m (lengthxwidthxheight), and the weight is about 5 tons. By using the testing system, a workpieces having an equivalent mass thicknesses of less than 130mm iron and diameter of less than 4)500mm can be tested, a thin iron sheet having a thicknesses of 3Opm behind an iron plate having a thickness of 3cm can be detected, and tiny cracks or seam clearance having an width of less than 20gm can be detected.
In the embodiment, testing tasks such as testing for seam clearance and small changes in the mass thicknesses, as weli as bubbling testing are decomposed and completed by testing systems with different parameters and different testing modes.
In the embodiment, testing for seam clearance and small changes in the mass thicknesses of the workpiece is realized in a mode of Co-60 source + large-pixel gas linear array detector DR scanning imaging'. A large-pixel detector has strong output signal minor statistical fluctuation, and facilitates testing for the changes in the mass thicknesses, The Co-60 source is characterized by stability over a long time, ease to operate, and high reliability; the gas detector is features low leakage current, high stability, minor temperature drift, and resistance to radiation. The DR scanning system composed of the Co-60 source and the gas detector has high measurement accuracy, stable performance over a long time, and is quite suitable for testing the seam clearance and the small changes in the mass thicknesses, In the embodiment, testing of the bubbling in a workpiece is realized in a mode of X-ray machine+small-pixel solid linear array detector CT tomographic imaging'. The CT tomographic imaging provides density distribution of the tested objects, detection of tiny defects and accurate positioning of the defects, and is the optimum means for testing bubbling and scaling.
The testing system of the embodiment adopts two ray sources (Co-60 and 450kV X-ray machine) and three detectors (small-pixel solid linear array detector, large-pixel gas linear array detector and micro-pixel planar array detector) which are used in combination to take full advantage of different ray sources and different detectors in a better manner, thus better meeting the testing requirements The X-ray machine has high radiation intensity, small source focal spot size, and is beneficial to improving the resolving power of the imaging system. The cobalt-60 source provides good single-energy property, for which the issue of ray beam hardening is absent, and Cobalt-60 has relatively high ray energy, stronger penetrating power and can be used for testing objects having bigger mass thicknesses. The small-pixel solid linear array detector is capable of shielding the scattering rays better, has higher detection efficiency, and clearer images can be obtained; and the micro-pixel planar array detector has smaller pixel size, a higher spatial resolution may be achieved, and three-dimensional images of the objects can be acquired with a single action, with the imaging being faster.
In the embodiment, the two ray sources and the three detectors above are integrated into a same testing platform, an up-and-down displacement layout as well as a composite and modular design mode are adopted, thus providing switchable combinations of different ray sources and different detectors, and different testing modes are organically combined, thus forming a comprehensive testing system.
The specific implementation modes of the present invention are described above in detail, but the present invention is not limited thereto, for example, a miniaturized X-ray accelerator may be used as a medium-energy and high-energy X-ray source.
Even if various variations are made to the present invention, steps or processes implemented on the basis of the spirit of the present invention, and the testing system constituted thereby should be interpreted as falling within the protection scope of the present invention.
Claims (10)
1. A method for combined my non-destructive testing, comprising steps of: a) irradiating a workpiece to be tested by using rays; b) receiving the rays penetrating through the workpiece by a detector and converting to digital signals; and c) obtaining radiation images of the workpiece through processing of the signals; wherein, -a combined detector comprising a solid linear array detector, a gas linear array detector and a pianar array detector are used as detectors, and DR scanning imaging, tomographic CT imaging or cone-beam CT imaging of the workpiece is realized by switching among different ray sources and testing units comprising different detectors; and -the combined ray source, the combined detectors, and a workpiece rotating table are all installed on a same rigid base.
2. The method according to claim 1, wherein the combined ray source is provided with a front coffimator at its ray outlet side, which front collimator is used for collimating the rays into fan-shaped beams or cone-shaped beams, and the combined detector is provided with a rear collimator at its ray inlet side; when the detector which is switched-on is a solid linear array detector or a gas linear array detector, the rear collimator is used for collimating the rays into small ray beams having comparable height and number with the detector unit, and the width of a collimating slit of the rear collimator is smaller than the width of the detector unit; during DR imaging, the rear collimator may creep in the direction of the width of the detector unit, and one set of projection data is acquired for each creep of the rear collimator, and the distance of each displacement is the width of the collimating slit.
3. A combined ray non-destructive testing system using the method according to claim I or 2, comprising: -a rigid base on which a ray source support, a workpiece rotating table and a detector support are sequentially arranged at intervals; -the ray source support is provided with a combined ray source comprising a y-ray source and an X-ray source, a switching mechanism for shifting different ray sources in the combined ray source in working positions, and a mechanism for allowing the displaced detectors up-and-down, front-and-back, left-and-right, and rotation operations; -the detector support is provided with a combined detector comprising a solid linear array detector, a gas linear array detector and a planar array detector, a switching mechanism used for displacing different detectors in the combined detector to working positions, and a mechanism used for allowing the displaced detectors up-and-down, front-and-back, left-and-right and rotation operations; -the ray source support is provided with a front collimators capable of collimating the rays emitted by the ray sources into fan-shaped beams or cone-shaped beams, and the detector support is provided with a rear collimator used for carrying out further collimation on the rays; -the gas linear array detector and the solid linear array detector are both of an arc-shaped structure, after the gas linear array detector and the solid linear array detector are displaced to the working positions, the ray incidence windows of various detector units in the detector are uniformly and closely arranged along a circular arc taking the source centre of the ray source in the working position as the centre of circle through which the central line of each detector unit passes, each rear collimator matching the gas linear array detector or the solid linear array detector is also of an arc-shaped structure taking the source centre of the ray source in the working position as the centre of circle, the collimating slit of the rear collimators is capable of collimating the fan-shaped ray beams into small ray beams which are in one-to-one correspondence with individual detector units in the detector, and the width of collimating slit is smaller than the width of the detector unit; during DR imaging, the rear collimator is closely adj acent to the gas linear array detector or the solid linear array detector, and may creep in direction of arrangement of the detector units, arid the distance for each creep is the dth of the collimating slit.
4, The testing system according to claim 3, wherein the width of the collimating slit is 1/2, 1/3, or 1/4 of the width of the detector unit.
5. The testing system according to claim 3 or 4, wherein the 7-ray source is a Co-60, Cs-137, or lr-192 radioisotope 7-ray source.
6. The testing system according to claim 3 or 4, wherein the X-ray source is a small focal spot X-ray machine, a micro-focus X-ray machine and/or an X-ray accelerator.
7. The testing system according to claim 3 or 4, wherein the planar array detector is an amorphous silicon planar array detector, an amorphous selenium planar array detector or a CMOS planar array detector.
8. The testing system according to claim 3 or 4, wherein the gas linear array detector is a gas-filled ionization chamber linear array detector, a multi-wire proportional chamber linear array detector or a Geiger counting tube linear array detector.
9. The testing system according to claim 3 or 4, wherein the solid linear array detector is a solid scintillator linear array detector or a semiconductor linear array detector.
10. The testing system according to claim 9, wherein the scintillator of the solid scintillator linear array detector is Nal, Csl, CdWO4. LaBr3 or LaCI3,
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| PCT/CN2012/079167 WO2014015490A1 (en) | 2012-07-26 | 2012-07-26 | Combined ray non-destructive testing method and system |
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| WO2023065671A1 (en) * | 2021-10-18 | 2023-04-27 | 同方威视技术股份有限公司 | Full-automatic detection system and method |
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| CN106290418A (en) * | 2016-08-31 | 2017-01-04 | 天津三英精密仪器股份有限公司 | A kind of CT detector being suitable for long sample |
| CN109932376B (en) * | 2019-04-30 | 2023-11-28 | 王振 | Liquid detection method and device |
| CN111458357A (en) * | 2020-04-21 | 2020-07-28 | 江苏省建筑工程质量检测中心有限公司 | Nondestructive detection system and detection method for construction quality of large vertical node of prefabricated concrete structure |
| CN111982936B (en) * | 2020-08-25 | 2023-10-10 | 绍兴市特种设备检测院 | X-ray automatic detection device for heat exchanger tube-tube plate welding seam |
| CN112393697B (en) * | 2020-11-09 | 2022-06-07 | 南京市计量监督检测院 | Method for nondestructively measuring internal size of medical luer gauge |
| CN115598152B (en) * | 2021-07-07 | 2024-04-19 | 同方威视技术股份有限公司 | Radiographic imaging system and radiographic imaging method |
| CN114280086B (en) * | 2021-11-16 | 2024-01-23 | 中国电子科技集团公司第三十八研究所 | CT imaging device |
| CN117169257A (en) * | 2023-11-01 | 2023-12-05 | 上海超群检测科技股份有限公司 | X-ray imaging device |
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| CN1343883A (en) * | 2001-09-21 | 2002-04-10 | 清华大学 | Detecting method and equipment for X-or gamma-radiation imaging |
| US20030179853A1 (en) * | 2002-03-20 | 2003-09-25 | Kensuke Amemiya | Radiological imaging apparatus and radiological imaging method and radiological imaging support method |
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| WO2014015490A1 (en) | 2014-01-30 |
| GB2519692B (en) | 2017-11-01 |
| GB201501147D0 (en) | 2015-03-11 |
| RU2598396C2 (en) | 2016-09-27 |
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