CN102284513A - Collimating mechanism for convexity instrument - Google Patents

Abstract

The invention relates to a collimation mechanism for a convexity meter, and belongs to the field of nuclear technology application. The collimation mechanism includes two sets of collimation devices with the same structure, and each set of collimation devices includes 3-stage collimators, and the collimators from the first stage to the third stage are arranged sequentially along the radiation direction of a radiation source. The first-level collimator includes a first tungsten plate; the second-level collimator includes second to fifth tungsten plates, two mounting plates, a bottom plate, a flat plate, and a fixing block, and the two mounting plates are placed on the flat plate, The two mounting plates are respectively connected with the second to the fifth tungsten plates, the two mounting plates are connected with the flat plate, the two mounting plates are connected, the flat plate is connected with the bottom plate, and a spring is pressed between the flat plate and the fixed block; the third level collimation The device includes the sixth tungsten plate, and the sixth tungsten plate is fixed by the top wire; after this three-level collimation, the ray beam emitted by the ray source becomes a collimated ray beam, which solves the problem that the convexity instrument lacks the collimation function for the ray beam emitted by the ray source Problems, improve the accuracy of product detection.

Description

A collimation mechanism for a convexity meter

technical field

The invention belongs to the application field of nuclear technology, and in particular relates to an alignment mechanism for a convexity instrument for detecting steel strips in a rolling production line of a steel mill.

Background technique

The crown meter is the key equipment for the production and control of steel strips, which can instantaneously and continuously measure the cross-sectional thickness distribution of steel strips. The structure of the crown meter, as shown in Figure 1, the main structure is a C-shaped frame 11, the measured steel strip 12 passes between the upper and lower arms of the C-shaped frame, the radiation source 13 is located inside the upper arm of the C-shaped frame, and the radiation source is Two X-ray machines, the two X-ray machines are identical, are placed at a certain distance apart; the radiation detector 14 is located inside the lower arm of the C-shaped frame, and includes two rows of detector arrays, and each row of detector arrays is distributed along a straight line, including several hundred an independent ray detector unit. Two rows of detector arrays correspond to two X-ray machines respectively.

Two X-ray machines emit X-rays downward at the same time, and the X-rays from two ray sources pass through the steel strip 12 to be tested from two different angles, and two rows of detectors are used to measure the attenuation degree of the two beams of X-rays respectively.

The convexity meter uses COMET MXR-225/02/FB X-ray machine. The X-ray beam emitted by this X-ray machine is an elliptical cone beam. The solid angle of the long axis is 90°, and the solid angle of the short axis is 30°. . The solid angle of the detector relative to the X-ray machine is only 45°×0.34°, which is much smaller than the angle of the ray beam emitted by the X-ray machine. Therefore, a collimator is required to collimate the ray beam emitted by the X-ray machine. The collimator not only shields the redundant rays emitted by the ray source for radiation safety, but more importantly, the redundant rays will generate a large number of scattered rays, which enter the detector, increase the noise of the detector, and reduce the noise of the device. measurement accuracy. Collimating the ray beam is a link that must be considered in many ray measuring equipment.

The part that emits rays in the X-ray machine is the target point. The target point is not an ideal point with a diameter of 0, but a disc with a certain diameter. The target point diameter of this X-ray machine is 5.5mm. The problem caused by the non-ideal point source of the target point is that after the ray beam emitted by the circular target point is collimated, three areas will be formed behind the collimator, the shielding area, the penumbra area and the total shadow area. The shielding area refers to the area where the target point cannot be seen at all. This area has no radiation exposure and is located on the outermost sides; the penumbra area refers to the area where part of the target point can be seen. This area is irradiated by radiation, but the intensity is relatively low. Low and unevenly distributed, this area is located between the shielding area and the total shadow area; the total shadow area refers to the area where all the target points can be seen, the intensity of rays in this area is the strongest, and the distribution is even. This area is located in the middle. Therefore, the ray in the total shadow area is most conducive to measurement. As shown in Figure 2, ray 23 is tangent to the left side of target point 21, and touches with point a on the left side of the collimating slit of collimator 22, and ray 24 is tangent to the right side of target point 21, and The lower left side of the collimation slit is connected to point b, and the other side is completely symmetrical. After the rays are collimated, the left side of point c and the right side of point f are shielding areas, cd area and ef area are penumbra areas, and de area For the total shadow area.

The convexity meter requires that the two rows of detector arrays are respectively located in the total shadow area of the corresponding X-ray machine.

At the same time, since the convexity meter uses two sets of X-ray machine-detector combinations, and the two X-ray machines are irradiated at the same time (some similar equipment adopts the way of staggered irradiation), it is also required that any row of detector arrays is only It is irradiated by the corresponding X-ray machine, but cannot be irradiated by the other X-ray machine. Since the distance between the two rows of detectors is only 0.46° relative to the solid angle of the X-ray machine, very high requirements are placed on the collimation.

In summary, the requirements for collimation of this convexity meter are: to shield redundant X-rays; to make the detector covered by the total shadow area of the ray beam of its corresponding X-ray machine; to distinguish the rays emitted from the two X-ray machines On, so that it only illuminates a certain row of detector arrays corresponding to it, and cannot illuminate another row of detector arrays.

Contents of the invention

The object of the present invention is to design a collimation mechanism for a convexity meter to improve the accuracy of product detection in order to change the problem that the existing convexity meter equipment lacks the collimation function of the ray beam.

The collimation mechanism for the convexity meter proposed by the present invention is characterized in that the collimation mechanism includes two sets of collimation devices with the same structure, and each set of collimation devices contains 3-stage collimators, from the first stage to the third stage The first-stage collimators are arranged sequentially along the ray direction of a ray source.

The first stage collimator may include a first tungsten plate with a rectangular hole in the middle, the longitudinal symmetry axis of the rectangular hole coincides with the long axis of the radiation beam emitted by the radiation source.

The second-stage collimator may include the second, third, fourth, and fifth tungsten plates, a first mounting plate, a second mounting plate with a semicircular groove in the middle, a bottom plate with guide rails and a central rectangular hole, Installed on the flat plate with a central rectangular hole on the bottom plate, the central rectangular hole of the flat plate corresponds to the central rectangular hole of the bottom plate, and the fixed block installed on the bottom plate, a spring is arranged between the flat plate and the fixed block to make the The flat plate can move horizontally on the base plate; the first and second mounting plates are symmetrically erected on both sides of the central rectangular hole of the flat plate, and the second tungsten plate and the third tungsten plate are placed horizontally on the sides of the first and second mounting plates respectively. On the top surface, the fourth tungsten plate and the fifth tungsten plate are placed upright on the inner sides of the first and second mounting plates respectively, and a collimating seam with adjustable width is formed between the fourth tungsten plate and the fifth tungsten plate .

The third-level collimator may include a sixth tungsten plate, and the upper and lower end surfaces on both sides of the sixth tungsten plate are respectively fixed by top wires.

After the three-stage collimation, the ray beam emitted by the ray source is effectively shielded in the direction of the long axis. In the direction of the short axis, it is collimated into a collimated ray beam that only irradiates the corresponding detector array arranged in a straight line, and this ray beam is all located in the total shadow area of the target point of the ray source, and will not irradiate another Rows of detector arrays are placed in parallel, and the distance between the two rows of detector arrays is only 0.46° relative to the solid angle of the ray source, which solves the problem that the convexity meter equipment lacks the collimation function for the ray beam emitted by the ray source. The accuracy of product detection is improved.

Description of drawings

Figure 1 is a schematic diagram of the structure of the crown meter.

Fig. 2 is a schematic diagram of the total shadow area and the penumbra area of the ray collimator.

Fig. 3 is a schematic diagram of the principle of the collimation mechanism of the present invention.

Fig. 4 is a schematic structural diagram of a first-stage collimator according to an embodiment of the present invention.

Fig. 5 is a schematic structural diagram of a second-stage collimator according to an embodiment of the present invention.

FIG. 6 is a schematic structural diagram of a third-stage collimator according to an embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example

The convexity meter aimed at by the present invention adopts the combination of two sets of ray source-detector arrays, as shown in Figure 1, the direction perpendicular to the end face 16 of the upper arm of the C-shaped frame is the X direction, and the direction perpendicular to the side surface 17 of the C-shaped frame is for the Y direction. In the X direction, as shown in Figure 3, in the figure, two X-ray machines are placed in the same linear direction in the X direction, the detector arrays are arranged along the X direction, and the two rows of detector arrays 35, 36 are parallel.

The X-ray beam emitted by the X-ray machine is an elliptical cone beam, the long axis is along the X direction, the short axis is along the Y direction, and the angle is 90°×30°. Also in the X and Y directions, the solid angle of the detector array relative to the X-ray machine is 45 ° * 0.34 °, as shown in Figure 3, in the Y direction, the distance between the two rows of detector arrays 35, 36 is relatively X The optomechanical angle is 0.46°. It is required that after collimation, the ray beam emitted by the X-ray machine is only irradiated on its corresponding detector array, and cannot be irradiated on another row of detector arrays. Moreover, since the target point of the X-ray machine has a certain diameter (5.5mm), the hologram and penumbra will be formed after the rays are collimated, and it is also required that the corresponding detector arrays are all located in the hologram.

As shown in FIG. 3 , the X-ray machine 31 and the detector array 36 are a combination 1, and the combination 2 is arranged symmetrically with the plane 38 (not shown in the figure). Correspondingly, there are two identical sets of collimation mechanisms, which are symmetrically arranged on the plane 38 . The first-stage collimator 32 , the second-stage collimator 33 , and the third-stage collimator 34 shown in FIG. 3 are a set of collimation mechanisms corresponding to combination 1 .

The collimation mechanism for the convexity meter consists of two sets of collimation mechanisms with the same structure, and each set of collimation mechanisms contains 3-level collimators, which are arranged sequentially along the ray direction of a radiation source from the first level to the third level .

The structure of the first-stage collimator, as shown in Figure 4, is a first tungsten plate with a thickness of 10mm, which is enough to completely block the rays emitted by the X-ray machine. The longitudinal direction of the first tungsten plate is provided with a rectangular hole 41 of 15×60 mm. During installation, the longitudinal axis of symmetry of the rectangular hole 41 coincides with the long axis of the X-ray beam. The ray beam can only pass through this hole, and the rest of the rays are completely blocked. After this level of collimation, the 90°×30° beam is reduced to 50°×10°. The required angle in the X direction is 45°, and no further collimation of the ray beam in the X direction is required. The relative position of this level of collimation and X-ray machine remains fixed.

The structure of the second-stage collimator, as shown in Figures 5a, 5b, and 5c, includes the second, third, fourth, and fifth tungsten plates 51, 52, 53, and 54 with a thickness of 10 mm. There is a first mounting plate 55 with a through hole in the middle of both sides, a second mounting plate 56 with a threaded hole on the position corresponding to the through hole on the first mounting plate, a bottom plate 513 with a guide rail and a central rectangular hole, with a center The flat plate 57 of rectangular hole, the central rectangular hole of this flat plate 57 corresponds to the position of the central rectangular hole of base plate 513, is installed on the fixed block 518 on the right side of base plate 513, as shown in Figure 5b, is installed on the left side of base plate 513 and Withstood the first top wire 519 of plate side, is installed on the left side of plate 57 and withstood the second top wire 520 of first mounting plate side, as shown in Figure 5 a; Also have elongated hole 516, also have elongated hole 59 on both sides longitudinally of the central rectangular hole of this plate 57, as shown in Figure 5c; The first, second mounting plate 55,56 are symmetrically erected and placed on the rectangular center of plate 57. Both sides in the longitudinal direction of the hole, the first and second mounting plates 55, 56 and the flat plate 57 are respectively connected by bolts 58 passing through the long holes 59, and the first and second mounting plates 55, 56 are connected by The bolt 510 passing through the through hole on the first mounting plate 55 and the bolt hole on the second mounting plate 56 is connected, and a compression spring 511 is passed on the bolt 510, and the two ends of the compression spring 511 respectively bear on the first and second The inner sides of the two mounting plates 55, 56; the flat plate 57 is placed on the base plate 513, and can be translated along the guide rail on the base plate 513, and the flat plate 57 and the base plate 513 are connected by bolts 515 passing through the elongated holes 516 ; The second tungsten plate 51 and the third tungsten plate 52 are placed horizontally on the top surfaces of the first and second mounting plates 55 and 56 respectively, and the second tungsten plate 51 and the third tungsten plate 52 are used to block the minor axis direction For redundant rays, the fourth tungsten plate 53 and the fifth tungsten plate 54 are placed upright on the inner side surfaces of the first and second mounting plates 55, 56 respectively, and the fourth tungsten plate 53 and the fifth tungsten plate 54 form a The collimation seam of adjustable width between 33,37 in Fig. 3, this collimation seam is along X direction; There are four springs 517 between this flat plate 57 and fixed block 518, and the two ends of these four springs 517 push respectively On the inner side of the flat plate 57 and the fixed block 518, in order to make the flat plate move horizontally to the left along the guide rail on the base plate, as shown in Figure 5b; a cylindrical pin 512 is placed on the flat plate 57, and the longitudinal middle part has a semicircular groove The second mounting plate 56 is rotatable about the cylindrical pin.

The position, width and angle of the collimating seam between the fourth tungsten plate 53 and the fifth tungsten plate 54 can be precisely adjusted. In order to ensure that the entire second-level collimator can still be adjusted conveniently after it is installed on the device, all adjustment functions are performed on the front and bottom surfaces shown in Figure 5a. After the ray beam is collimated at this level, its total shadow area just covers the detector array 36 , as shown in FIG. 3 .

The position of the collimating seam is realized by rotating the first top wire 519 . Rotate the first jacking wire 519 to the right to make the flat plate 57 drive the collimation seam to translate to the front guide rail 514; The screw pitch of the jacking screw is 1 mm, and one rotation of the jacking screw corresponds to a translation of the plate 57 by 1 mm. Therefore, by controlling the rotation angle of the jacking screw, the position of the plate 57, that is, the alignment seam, can be precisely controlled. The following adjustments are similar to this.

The width of the collimating slit is adjusted by two bolts 510 . The two bolts are adjusted synchronously. Turn two bolts to the right, the first mounting plate 55 and the second mounting plate 56 are pulled closer by the bolts, and the width of the collimation seam shrinks; Open under pressure, the width of the collimation slit increases.

The angle of the collimating seam is adjusted by two jacking wires 520 . The second top wire 520 is composed of left and right two top wires, and the two top wires are adjusted oppositely, one of them is rotated right, and the other is rotated left, and the rotation angle is the same. By making the first mounting plate 55 and the second mounting plate 56 rotate around the cylindrical pin 512 as a whole, the angle of the collimating slit changes accordingly.

After adjusting the position, width and angle of the alignment seam, tighten two bolts 515 from under the bottom plate 513 to fix the flat plate 57 and the bottom plate 513; tighten four bolts 58 to make the first mounting plate 55 and the second mounting plate 56 Fixed with plate 57.

Described tertiary collimator, as shown in Figure 6, comprises the support member that thickness is the 6th tungsten plate 61 of 10mm and tungsten plate 61 two ends identical, the both sides of this 6th tungsten plate 61 are respectively made of top wire 62, 63 are fixed. By adjusting the top wire, the positions of both ends of the sixth tungsten plate 61 can be precisely adjusted and fixed respectively, so that the position and the angle in the horizontal direction of the sixth tungsten plate 61 can be precisely adjusted. The function of the third-stage collimator, as shown in FIG. 3 , is to block the penumbra region of the detector array 35 emitted by 31 and collimated by 33 .

After this three-stage collimation, the ray beam emitted by the X-ray machine is effectively shielded in the direction of the long axis. In the short axis direction, it is collimated into a collimated ray beam that only irradiates the corresponding detector array arranged in a straight line, and the ray beam is all located in the total shadow area of the target point of the X-ray machine, and the collimated ray beam does not It will illuminate another row of parallel detector arrays separated by only 0.46°.

Claims (4)

1. a profile gauge collimation mechanism is characterized in that, this collimation mechanism comprises the collimator apparatus of two cover same structures, and every cover collimation device includes 3 grades of collimaters, arranges successively from the first order to third level collimater along a radiogenic directions of rays.

2. profile gauge collimation mechanism as claimed in claim 1 is characterized in that, this first order collimater comprises that the middle part has the first tungsten plate of rectangular opening, and vertical symmetry axis of this rectangular opening overlaps with the major axis of the beam of radiographic source emission.

3. profile gauge collimation mechanism as claimed in claim 1, it is characterized in that, this second level collimater comprise second, third, the 4th, the 5th block of tungsten plate, first installing plate, the centre has second installing plate of half slot, the base plate that has guide rail and central rectangular aperture, be installed in the flat board that has central rectangular aperture on the base plate, this dull and stereotyped central rectangular aperture is corresponding with the central rectangular aperture position of base plate, be installed in the fixed block on the base plate, be provided with spring between this flat board and the fixed block, with so that flat board can on base plate, move horizontally; This first, second installing plate symmetry is erect the both sides that place dull and stereotyped central rectangular aperture, this second tungsten plate, the 3rd tungsten plate level respectively place on the end face of first, second installing plate, the 4th tungsten plate, the 5th tungsten plate are erect respectively on the medial surface that places first, second installing plate, form the collimating slit of adjustable width between the 4th tungsten plate, the 5th tungsten plate.

4. profile gauge collimation mechanism as claimed in claim 1 is characterized in that, this third level collimater comprises that the upper and lower end face of the 6th tungsten plate, the 6th tungsten plate both sides fixed by jackscrew respectively.

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