CN106524948B - UO2Pellet system for detecting verticality and its detection method - Google Patents

Abstract

The invention discloses a UO ₂ core block verticality detection system and a detection method thereof, wherein the detection system includes a host computer and a detection device, the detection device includes a base, a guide rail is provided on the base, and a slide rail is provided on the guide rail. A stepper motor is installed at one end of the guide rail, and a core block positioning device is provided on the upper side of the slide table; a line laser scanner is provided on both sides of the guide rail; the upper computer is connected with the stepper motor and the two-line laser scanner connected; the detection method includes the following steps: 1) placing the UO ₂ pellet to be tested on the pellet positioning device; 2) synchronously scanning and detecting the end face of the UO ₂ pellet to be tested by a two-line laser scanner; 3) The upper computer performs data processing through the data processing system to obtain the verticality of the UO ₂ core block to be tested. The invention can quickly detect the UO ₂ pellets, and simultaneously detect a plurality of UO ₂ pellets, thereby greatly improving the detection efficiency of the UO ₂ pellets.

Description

UO2 Pellet Perpendicularity Testing System and Its Testing Method

technical field

The invention relates to the technical field of product detection, in particular to a detection system and a detection method for the perpendicularity between the end face of a UO ₂ core block with a columnar structure and the axis.

Background technique

During the production and processing of nuclear fuel, the gap between the UO ₂ (fuel) pellet and the cladding tube is an important factor affecting the temperature of the nuclear fuel pellet. Since the fuel pellet is cylindrical as a whole, and its two ends have grooves so that the two ends are ring-shaped, the perpendicularity between the end surface of the fuel pellet and the axis directly affects the accuracy of the gap measurement between the nuclear fuel pellet and the cladding tube Therefore, in the production process of UO ₂ pellets, it is particularly important to test the verticality accuracy of the pellets.

The traditional detection methods mainly include: sleeve method, V-shaped bearing seat method, mandrel method, etc. In order to realize the rapid and high-precision automatic detection of the verticality of fuel pellets, the most widely used method is the V-shaped support seat method. The detection devices mainly used in this method include bases, brackets, rotating tables, two-dimensional moving tables, tilting tables, and lifting tables. table, V-shaped positioning block, fastening screw and grating displacement sensor; when measuring, first place the tested nuclear fuel pellet on the lifting platform, and use the fastening screw and V-shaped positioning block to fix it to ensure that the tested pellet When the rotary table rotates, the measuring head of the grating displacement sensor always contacts the ring end face of the pellet under certain stress; secondly, the stepper motor drives the rotary table to drive the fuel pellets to rotate. The displacement of the point relative to the reference point is transmitted to the peripheral conversion circuit in the form of voltage, and then converted into a displacement value. The difference between the maximum and minimum displacement value is the measured value of the verticality of the fuel pellet.

However, for the lifting table in the detection device, the flatness of the table itself and the flatness of the end face of the end surface of the nuclear fuel pellet in contact with the lifting table table will bring great errors to the measurement, resulting in low measurement accuracy; Moreover, in the measurement process, only one nuclear fuel pellet can be measured at a time, so that the measurement process is slow and the measurement efficiency is low.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is how to solve the problems of low measurement accuracy and low measurement efficiency of UO ₂ pellet verticality in the prior art, and provide a UO ₂ pellet verticality detection system and its The detection method can quickly detect the UO ₂ pellets, and simultaneously detect a plurality of UO ₂ pellets, thereby greatly improving the detection efficiency of the UO ₂ pellets.

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a UO ₂ core block verticality detection system, including a host computer and a detection device, is characterized in that: the detection device includes a rectangular base, on which the There is a guide rail in its length direction, and a slide table is arranged on the guide rail. The upper side of the slide table is a plane; a stepping motor is installed at one end of the guide rail, and the output shaft of the stepping motor is connected with a threaded rod. It is located above the guide rail, and its length direction is consistent with the length direction of the guide rail. The slide table is provided with a screw hole through the slide table corresponding to the screw rod, and is matched with the screw rod through the screw hole, and can be driven by a stepping motor. The slide table moves along the length direction of the screw;

A core block positioning device is provided on the upper side of the slide table. The core block positioning device includes a support seat and a pressing bracket. The support seat is fixedly connected with the slide table, and its length direction is consistent with the length direction of the slide table. There are several V-shaped positioning grooves running through both sides of the positioning seat along its length direction, and the length direction of the positioning grooves is perpendicular to the length direction of the support seat; the compression bracket includes two columns and a compression rod, wherein the two The uprights are installed on the slide table and are respectively located at both ends of the supporting base. One end of the pressing rod is hinged to one of the uprights, and a limiting groove is provided above the other upright. When the free end of the pressing rod rotates When it reaches the top of the column, it can enter the limiting groove; a positioning pin is arranged on one side of the limiting groove, and a positioning hole is provided corresponding to the positioning pin on the other side of the pressing rod and the limiting groove. After the rod enters the limiting groove, the pressing rod can be positioned by the positioning pin; on the pressing rod, an elastic pressing column is respectively provided corresponding to each positioning groove, and the pressing column passes through the pressing bar from top to bottom. Rod, the upper part of which is threadedly connected with the pressing rod, and the lower part extends into the positioning groove;

Corresponding positions on both sides of the middle of the guide rail are respectively equipped with a line laser scanner, the laser head of the line laser scanner can face the positioning groove, the plane where the laser beam emitted by it is a vertical plane, and is aligned with V The section of the type positioning groove is vertical;

The upper computer is connected with the stepping motor through the driver, and the data output end of the two-line laser scanner is connected with the upper computer at the same time.

Further, the guide rail is provided with guide grooves running through both ends along its length direction, and the lower side of the slide table is provided with a sliding block corresponding to the guide grooves.

Further, the compression column includes a sleeve and a pressure column, the upper end of the sleeve is a closed structure, and threads are provided on the outer wall of the sleeve; the upper end of the compression column extends into the sleeve from the lower end of the sleeve. In the tube, a spring is arranged between the upper end of the pressure column and the upper end of the sleeve, and the two ends of the spring are respectively fixedly connected with the sleeve and the pressure column.

A kind of detection method of above-mentioned UO ₂ pellet verticality detection system, it is characterized in that: comprise the steps:

1) Place several _UO2 pellets to be tested on the support seat of the pellet positioning device, and press and fix the _UO2 pellets to be tested by pressing the bracket;

2) Control the rotation of the stepper motor through the host computer, and drive the pellet positioning device to move from one side of the line laser scanner to the other side at a set speed; during the movement of the pellet positioning device, the two-line laser scanning The device scans and detects the end face of the UO ₂ core block to be tested synchronously, and transmits the detected data to the host computer;

3) After the host computer receives the data collected by the two-line laser scanner, it processes the data through the data processing system to obtain the perpendicularity between the end face of the UO ₂ pellet to be tested and the axis.

Further, in step 3), the data processing process is as follows:

a. After the data processing system is started, input the data collected by the two-line laser scanner into the data processing system;

b. Judging whether the input data block is biased: if the data block is biased, the database is biased, wherein the database is a data collection of an end face of the _UO2 core block to be tested collected by the line laser scanner , the data set is a two-dimensional data matrix;

c. The data in the data block is sequentially processed by Hough transform to remove irrelevant points and 3δ principle to remove stray data points;

d. Self-adaptive calibration of the axis line of the UO ₂ pellet to be tested;

e. Carry out Bezier curve fitting to the data;

f. Finally, calculate the perpendicularity between the end face of the UO2 pellet to be tested and the axis line according to the Bezier curve.

Compared with prior art, the present invention has following advantage:

1. The detection is convenient and fast, and can detect multiple UO2 pellets at one time, thereby greatly improving the detection efficiency.

2. The measurement data is less affected by the outside world, thereby greatly reducing the measurement error caused during the measurement process and improving the measurement accuracy.

3. In the process of verticality calculation, the data is processed better, so that the obtained verticality is more accurate.

Description of drawings

Fig. 1 is a side view of the detection device of the present invention.

Fig. 2 is a top view of the detection device of the present invention.

Fig. 3 is a schematic structural view of the pellet positioning device.

Figure 4 is a schematic diagram of scanning.

Fig. 5 is a processing flowchart of the data processing system.

Figure 6 is a schematic diagram of 3δ processing.

Figure 7 is a fitting curve diagram.

In the figure: 1—base, 2—guide rail, 3—sliding table, 4—stepping motor, 5—chip positioning device, 51—support seat, 52—column, 53—pressing rod, 54—elastic pressing column , 6—line laser scanner, 7—UO ₂ pellets to be tested.

Detailed ways

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

Embodiment: Referring to Fig. 1-Fig. 4, a UO ₂ core block verticality detection system includes a host computer and a detection device, and the detection device includes a rectangular base 1, on which a guide rail 2 is provided along its length direction, A slide table 3 is fitted on the guide rail 2, and the upper side of the slide table 3 is a plane; On the side, corresponding to the guide groove is provided with a sliding block that cooperates with it, so that the slide table 3 has a larger sliding distance range and is less affected by the guide rail 2 . One end of the guide rail 2 is equipped with a stepping motor 4, and the output shaft of the stepping motor 4 is connected with a threaded mandrel; The slide table 3 is provided with a screw hole through the slide table 3 corresponding to the screw rod, and is matched with the screw rod through the screw hole, and the stepper motor 4 can drive the slide table 3 to move along the length direction of the screw rod.

A core block positioning device 5 is provided on the upper side of the slide table 3, and the core block positioning device 5 includes a support seat 51 and a pressing bracket. The support seat 51 is fixedly connected with the slide table 3, and its length direction is consistent with the length direction of the slide table 3. The support seat 51 is provided with several V-shaped positioning grooves running through both sides of the positioning seat along its length direction. The longitudinal direction of the groove is perpendicular to the longitudinal direction of the support seat 51 . Described pressing bracket comprises two columns 52 and a pressing bar 53, and wherein, two columns 52 are installed on the slide table 3, and are respectively positioned at the two ends of support seat 51; One end of described pressing bar 53 and one of them The column 52 is hinged, and a limiting groove is provided above the other column 52. When the free end of the pressing rod 53 rotates above the column 52, it can enter the limiting groove; one side of the limiting groove is provided with a positioning groove. Pin, on the other side of the compression rod 53 and the spacer groove, corresponding to the positioning pin is provided with a positioning hole, after the compression rod 53 entered the spacer groove, the compression rod 53 can be positioned by the positioning pin. On the compression rod 53, an elastic compression column 54 is respectively provided corresponding to each positioning groove, and the compression column passes through the compression rod 53 from top to bottom, and its upper part is threadedly connected with the compression rod 53, and the lower part extends into the positioning In the groove; wherein, the compression column includes a sleeve and a pressure column, the upper end of the sleeve is a closed structure, and a thread is provided on the outer wall of the sleeve; the upper end of the compression column extends from the lower end of the sleeve A spring is arranged between the upper end of the pressing column and the upper end of the sleeve, and the two ends of the spring are fixedly connected with the sleeve and the pressing column respectively.

Corresponding positions on both sides of the guide rail 2 middle part are respectively provided with a line laser scanner 6, the laser head of the line laser scanner 6 can face the positioning groove, and the plane where the laser beam it sends is a vertical plane, And perpendicular to the section of the V-shaped positioning groove.

The host computer is connected to the stepper motor 4 through a driver, and the data output terminal of the two-line laser scanner 6 is connected to the host computer at the same time.

Referring to Fig. 5, a detection method based on the above-mentioned UO ₂ pellet verticality detection system comprises the following steps:

1) Place several UO ₂ core blocks 7 to be tested on the support seat 51 of the core block positioning device 5, and press and fix the UO ₂ core blocks 7 to be tested by pressing the bracket.

2) Control the rotation of the stepper motor 4 through the host computer, and drive the pellet positioning device 5 to move from one side of the line laser scanner 6 to the other side at a set speed; during the movement of the pellet positioning device 5, the two The line laser scanner 6 scans and detects the end face of the UO ₂ core block 7 to be tested synchronously, and transmits the detected data to the host computer.

3) After receiving the data collected by the two-line laser scanner, the host computer performs data processing through the data processing system to obtain the perpendicularity between the end face of the UO ₂ pellet 7 to be tested and the axis.

In step 3), the data processing process is as follows:

a. After the data processing system is started, input the data collected by the two-line laser scanner into the data processing system.

b. Judging whether the input data block is biased: if the data block is biased, the data block is biased, wherein the database is the data of an end face of the _UO2 core block to be tested collected by the line laser scanner Set, the data set is a two-dimensional data matrix (horizontal and vertical coordinates are the corresponding index values of the UO ₂ core block end face data in the X direction and Y direction).

In the process of offset processing, because the end face data (useful data, called data block) is in the range of the whole data (including useful data and useless data), firstly calculate the average longitudinal index of the end face data (data block) then confirm At the location of the entire longitudinal index range (Y _min , Y _max ), the offset of the data block can be judged according to the relationship between the two. That is, if Then the data block is biased downward (the data block is below all data areas); if The data block is biased up (the data block is above all data areas); according to the above bias situation, the data block is biased to ensure that

c. The data in the data block are sequentially processed by Hough transform to remove irrelevant points and 3δ principle to remove stray data points.

In the process of Hough transform removing irrelevant points:

In xy space, for a point (x ₀ , y ₀ ), the straight line passing through this point must satisfy y ₀ =k*x ₀ +b, where k is the slope of the straight line, and b is the intercept of the straight line;

The above formula can be transformed into b=y ₀ -k*x ₀ , which can be regarded as a straight line equation in kb space with -x ₀ as the slope and y ₀ as the intercept (k and b are variables).

It can be seen that a straight line on the k-b space represents all straight lines passing through a specific point in the x-y space, and a specific straight line on the x-y space is represented by a specific point on the k-b space.

For each data point in the data block, draw a straight line in the k-b space; at the intersection of each straight line, we adopt the method of "voting", that is, accumulation; in other words, if n straight lines intersect at one point, then The value of this point is n; traverse the k-b space to find the point where the local maximum (extreme value) appears (that is, the local maximum n value), and the coordinates (k, b) of these points are the slopes of the possible straight lines that may appear in the data block and the intercept; according to the Hough transform, three local maximum n values can be obtained, and each n value corresponds to a straight line.

According to the obtained three straight lines (left chamfer straight line, end face straight line and right chamfer straight line), the data range (x_left, x_right) of the end face is further narrowed, so as to find out the data of the annular end face.

3δ principle in the process of removing stray data points:

Referring to Fig. 6, for the data points within the determined range (x_left, x_right), use the method of mathematical statistics to eliminate the noise points on the end face. The 3δ principle, that is, the 3 standard deviation principle, performs normal distribution statistics on the data points corresponding to the (x_left, x_right) range, and calculates its standard deviation and average value, and removes (u-3δ, u+3δ) (where u is The data noise other than the average value) further ensures the reliability of the data.

d. Perform adaptive correction on the axis line of the UO ₂ pellet to be tested:

Although _the detection system preliminarily guarantees that the axis line of the UO ₂ pellet to be tested is "perpendicular" to the laser heads of the two sensors; The included angle is slightly greater than 90 degrees (or slightly less than 90 degrees), and this angular deviation will be superimposed on the final perpendicularity.

The above angular deviation is caused by the superposition of the processing accuracy of the V-groove and the assembly accuracy of the sensor. The impact of the angular deviation can be reflected from the data output by the sensor, which also provides us with a way to find the inclination of the central axis: by Sensor data inversion.

Therefore, we take x, z and y, z to form two two- _dimensional matrices (x, z) and (y, z ), use the least squares method to calculate the left and right, up and down inclinations of the central axis for (x, z) and (y, z) respectively; where, z is the sensor data, x, y is its two-dimensional index; use the obtained inclination The degree in turn compensates the pellet end face data (done in conjunction with the 2D index of each data).

e. Carry out Bezier curve fitting to the data;

Since the end face of the UO ₂ pellet is annular, the data processed by the above steps are on an approximate torus. In the Bezier curve fitting process, a circle is used to approximate the torus, and the circle is divided into Four quarter arcs are approximated by third-order Bezier curve fitting for each quarter arc.

First solve for the quarter arc in the first quadrant:

P(t)=A*(60-t)*3+B*3(60-t)*2t+C*3(60-t)*2t+D*3t, (t belongs to [0, 60]) ; Among them, A, B, C and D are four control points, which are A(0,60), B(h,60), C(60,h) and D(60,0); (60 is the circle radius , as a specific embodiment)

P(30)＝A*27000+B*81000+C*81000+D*27000 (P(30) means the value when t is 30);

Substituting four control points A(0,60), B(h,60), C(60,h) and D(60,0), the coordinate point of P(30) can be solved:

x ² +y ² =(6480000+81000h) ² +(6480000+81000h) ² =60 ² ;

Solve for h: h=-79.99947622; finally get:

From then on, the quarter arc of the first quadrant is completed; similarly, the quarter arcs of the second quadrant, the third quadrant and the fourth quadrant are solved.

The arcs of the four quadrants are spliced together to form a complete circle, which is used to approximate the torus. As mentioned above, the circular end face data is a data block, and the z value corresponding to the circle formed by Bezier curve fitting is used for calculating the verticality.

f. Finally, calculate the perpendicularity between the end face of the UO ₂ pellet to be tested and the axis line according to the Bezier curve.

See Figure 7. In the error theory, the verticality can be represented by the range (size) between the two dotted lines, which means that the smaller the distance between the two dotted lines, the better the verticality. The solid vertical line in the figure is the central axis. The lower dotted line is the measurement end surface of the sensor, the upper dotted line is the surface parallel to the sensor measurement surface (the upper limit of the fluctuation of the core block end surface), and the solid line is the fluctuation curve of the core block end surface.

Therefore, the verticality of the end surface relative to the central axis can be converted into the flatness of the end surface, that is, the curve fitted by the third-order Seibel curve (the index values x and y in the two directions of the z value are fitted) in Z The maximum difference on the axis (max(z)-min(z)), in other words, the perpendicularity is equal to the maximum difference on the Z axis of the curve fitting the third-order Seibel curve.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the technical solutions. Those skilled in the art should understand that those who modify or replace the technical solutions of the present invention without departing from the present technology The purpose and scope of the scheme should be included in the scope of the claims of the present invention.

Claims (5)

1. A UO ₂ core block verticality detection system, including a host computer and a detection device, is characterized in that: the detection device comprises a rectangular base, on which a guide rail is provided along its length, and a slide rail is provided on the guide rail. The upper side of the sliding table is a plane; a stepping motor is installed at one end of the guide rail, and the output shaft of the stepping motor is connected with a threaded rod, which is located above the guide rail, and its length direction is consistent with the length direction of the guide rail , the slide table is provided with a screw hole through the slide table corresponding to the screw rod, and is matched with the screw rod through the screw hole, and the stepping motor can drive the slide table to move along the length direction of the screw rod; A core block positioning device is provided on the upper side of the slide table. The core block positioning device includes a support seat and a pressing bracket. The support seat is fixedly connected with the slide table, and its length direction is consistent with the length direction of the slide table. There are several V-shaped positioning grooves running through both sides of the positioning seat along its length direction, and the length direction of the positioning grooves is perpendicular to the length direction of the support seat; the compression bracket includes two columns and a compression rod, wherein the two The uprights are installed on the slide table and are respectively located at both ends of the supporting base. One end of the pressing rod is hinged to one of the uprights, and a limiting groove is provided above the other upright. When the free end of the pressing rod rotates When it reaches the top of the column, it can enter the limiting groove; a positioning pin is arranged on one side of the limiting groove, and a positioning hole is provided corresponding to the positioning pin on the other side of the pressing rod and the limiting groove. After the rod enters the limiting groove, the pressing rod can be positioned by the positioning pin; on the pressing rod, an elastic pressing column is respectively provided corresponding to each positioning groove, and the pressing column passes through the pressing bar from top to bottom. Rod, the upper part of which is threadedly connected with the pressing rod, and the lower part extends into the positioning groove; Corresponding positions on both sides of the middle of the guide rail are respectively equipped with a line laser scanner, the laser head of the line laser scanner can face the positioning groove, the plane where the laser beam emitted by it is a vertical plane, and is aligned with V The section of the type positioning groove is vertical; The upper computer is connected with the stepping motor through the driver, and the data output end of the two-line laser scanner is connected with the upper computer at the same time. 2. The UO ₂ core block verticality detection system according to claim 1, characterized in that: said guide rail is provided with guide grooves running through its two ends along its length direction, and the lower side of said slide table corresponds to the guide groove The slot is provided with a slide block matched therewith. 3. The UO ₂ pellet verticality detection system according to claim 1, characterized in that: the compression column comprises a sleeve and a pressure column, the upper end of the sleeve is a closed structure, and on the outer wall of the sleeve There are threads on the top; the upper end of the pressure column extends into the sleeve from the lower end of the sleeve, and a spring is arranged between the upper end of the pressure column and the upper end of the sleeve, and the two ends of the spring are respectively fixed with the sleeve and the pressure column connect. 4. a detection method of UO ₂ pellet verticality detection system as claimed in claim 1, is characterized in that: comprise the steps: 1) Place several UO ₂ pellets to be tested on the support seat of the pellet positioning device, and press and fix the UO ₂ pellets to be tested by pressing the bracket; 2) The rotation of the stepper motor is controlled by the host computer, and the pellet positioning device is driven to move from one side of the line laser scanner to the other side at a set speed; during the movement of the pellet positioning device, the two-line laser scanning The device scans and detects the end face of the UO ₂ core block to be tested synchronously, and transmits the detected data to the host computer; 3) After the host computer receives the data collected by the two-line laser scanner, it processes the data through the data processing system to obtain the perpendicularity between the end face of the UO ₂ pellet to be tested and the axis. 5. A detection method of the UO ₂ pellet perpendicularity detection system as claimed in claim 4, characterized in that: in step 3), the data processing process is as follows: a. After the data processing system is started, input the data collected by the two-line laser scanner into the data processing system; b. Judging whether the input data block is biased: if the data block is biased, the database is biased, wherein the database is a data collection of an end face of the _UO2 core block to be tested collected by the line laser scanner , the data set is a two-dimensional data matrix; c. The data in the data block is sequentially processed by Hough transform to remove irrelevant points and 3δ principle to remove stray data points; d. Self-adaptive calibration of the axis line of the UO ₂ pellet to be tested; e. Carry out Bezier curve fitting to the data; f. Finally, calculate the perpendicularity between the end face of the UO ₂ pellet to be tested and the axis line according to the Bezier curve.