JPH0617794B2 - Bending and twisting inspection system for objects - Google Patents

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

The present invention relates to a bending / twisting inspection apparatus for a prismatic elongated object whose target is a fuel assembly for a fast breeder reactor, for example.

[Prior art and its problems]

As is well known, the fuel assembly described above is formed as a stainless steel hexagonal column body integrally formed by welding and joining an entrance nozzle portion and a trumpet tube containing a fuel element. Is normally inspected for deformation and the like before it is delivered to the reactor facility after being assembled and manufactured.
In this inspection, in addition to the external dimension inspection of the fuel assembly, the visual inspection for the presence of scratches on the surface, etc., bending and twisting inspection are important inspection items. That is, as described above, the fuel assembly is formed as a welded joint between the entrance nozzle portion and the trumpet pipe, and therefore, due to welding distortion and manufacturing error in the welding process, the fuel assembly is along the longitudinal direction. It is easily bent and twisted. On the other hand, the fuel assembly is strictly regulated so that its dimensional accuracy is within an allowable error of the order of μm in consideration of loadability to a nuclear reactor. In this regard, in the conventional inspection like this, various inspections are carried out by visually measuring or using a contact type sensor with the fuel assembly lying on the floor. In this method, the fuel is first placed in the horizontal posture. Therefore, particularly in bending, the fuel assembly is bent due to the influence of gravity, and an accurate inspection result cannot be obtained. Further, in the method using the contact type sensor, not only high inspection accuracy cannot be obtained due to wear of the contact portion of the sensor in the inspection process, but also the surface of the fuel assembly is scratched or soiled. There is a fear. In addition, if the sensor process for inspecting the fuel assembly as an inspected object is not a remote control method, there is a possibility that the inspector may be exposed to radiation.

[Object of the Invention]

The present invention has been made in view of the above points, and eliminates the problems of the above-described conventional inspection method and provides a non-contact type remote control method for bending, twisting, etc. along the longitudinal direction of the object to be inspected. It is an object of the present invention to provide a bending / twisting inspection device for an object, which can be inspected with high accuracy.

[Points of the Invention]

According to the present invention, an inspected object holding mechanism for supporting an inspected object in an upright posture and two sets of non-contact arranged in parallel with each other with two sensors arranged in a pair so as to sandwich the inspected object. Type displacement sensor, an elevating drive mechanism for moving the displacement sensor up and down along an object to be inspected, and an arithmetic control unit for arithmetically processing output data of the displacement sensor. An imaginary center line in the axial direction passing through the cross-sectional center point of the reference measurement position obtained from the output data of the displacement sensor measured for each facing surface at the reference measurement position set on the axis of the inspected object in the holding state, And a vertically divided virtual center plane obtained from the output data of the displacement sensor at the reference measurement position set on the axis for each facing surface of the inspected object, and at the target measurement position displaced from the reference measurement position. At the center point of the cross section of the target measurement position obtained from the output data of the displacement sensor for each facing surface of the inspection object, and at the target measurement position obtained from the output data of the displacement sensor at the target measurement position displaced from the reference measurement position Comparing with the twist center plane corresponding to the virtual center plane of, the relative deviation of the axial center between the reference measurement position and the target measurement position, and the average of the relative twist angles from the relative deviation of the center plane. The value is calculated and the degree of bending and twisting along the longitudinal direction of the object to be inspected is simultaneously detected from the comparison calculation result.

Examples of the invention

FIG. 1 is a block diagram of an inspection apparatus according to an embodiment of the present invention in which a fuel assembly of a nuclear reactor is an object to be inspected, and FIG. 2 is a system diagram of the inspection system. In the figure, 1 is a fuel assembly, 11 is an entrance nozzle portion of the fuel assembly 1, 12 is a trumpet tube portion that accommodates fuel elements, and 13 is a top handling head 13. Reference numeral 14 indicates a welded portion between the entrance nozzle portion 11 and the trumpet tube portion 12. On the other hand, the inspection device is the entrance nozzle unit 1
Object holding mechanism 2 for receiving 1 to stand up and hold the fuel assembly 1 in a vertical posture, a non-contact type displacement sensor 3 spaced apart from the fuel assembly 1 and facing the side surface thereof, and the displacement sensor. The fuel assembly 3 includes a remote-operated lift drive mechanism 4 for moving up and down along the longitudinal direction of the fuel assembly 1, an arithmetic control unit 5, an inspection monitor unit 6, and the like. The inspected object holding mechanism 2 described above receives the entrance nozzle portion 11 of the fuel assembly 1 from below and holds the holding cylinder 21 in an upright posture, and pivots the holding cylinder 21 around its axial center. Revolving drive unit 22 and holding cylinder 2
The encoder 23 detects one turning position. On the other hand, the displacement sensor 3 employs a highly accurate capacitance type sensor having a resolution of about 35 μm, and two sensors are provided on each side of the fuel assembly 1 with the sensor 1 interposed therebetween.
Two sets of sensors 31 to 34 are arranged in parallel and face each other. The lift drive mechanism 4 includes a lift table 41 having the displacement sensor 3 mounted thereon and a feed screw mechanism 4 for vertically moving the table 41 along the fuel assembly 1.
2, a drive unit 43 of the feed screw mechanism 42, and an elevation position detection encoder 44 of the sensor 3 mounted on the table. Both the inspected object holding mechanism 2 and the lifting drive mechanism 4 are of a remote operation type which operates according to an operator's command from the outside. The second
The arithmetic control unit 5 shown in the drawing is the displacement sensors 31 to 31 described above.
34 and each of the encoders 23 and 44, and is provided with an arithmetic function for processing the data. Further, the inspection monitor unit 6 has a printer for outputting the inspection result as numerical data and a display for outputting as an image. Equipped. Reference numeral 51 is a signal converter of the sensor. With the above configuration, the fuel assembly 1 is held in the upright posture by the inspected object holding mechanism 2, and the displacement sensors 31 to 34 are placed on the side surfaces of the fuel assembly 1 so as to face each other in a non-contact manner. As shown in the figure, the origins X of the lifting drive system described above are obtained by finding the facing distances d _{1 to} d ₄ between the sensors 31 to 34 and the side surfaces of the fuel assembly 1 facing the sensors 31 to 34 from the sensor output.
Since the distances L ₁ and L _{2 to} the tip of each sensor and the distance L ₃ between the sensors of each set are known, the cross-sectional center point O of the fuel assembly 1 at the sensor facing position and the above Sensors 31 and 33, and 32 and 34
It is possible to set the vertical split center plane P of the regular hexagonal fuel assembly 1 that passes through the center points m and n of the fuel assembly 1 measured on the line connecting the centers of. The calculation of the center point O of the cross section will be described below with reference to FIG. I. Suppose that the surfaces to be measured are A and D surfaces. B. The facing distance from the A side reference surface of the sensor to the A surface is d
₁ , d ₂ , and the facing distances from the D-side reference surface of the sensor to the D surface are d ₃ and d ₄ . Coordinate from the origin X of the lifting drive system until the middle point m _{[L 2 -L 1 - (d 1} + d 3) ] _{/ 2 + L 1 + d 1} = (L 2 + L 1 + d 1 -d 3/2 origin of elevation driving system Coordinates from X to the central point n [L ₂ −L ₁ − (d ₂ + d ₄ )] / 2 + L ₁ + d ₂ = (L ₂ + L ₁ + d ₂ −d ₄ ) / 2 C. Center points of the A and D surfaces O is determined as the center between the coordinates of the center point m and the coordinates of the center point n, and the coordinates from the origin X of the lifting drive system to the point O = (coordinates of m point + coordinates of n point) / 2 = (L ₂ + L ₁ ) /
_{2+ (d 1 + d 2 -d} 3 -d 4) / 4 d. The center coordinates between the B and E planes and the C and F planes are similarly calculated. It should be noted that the vertical split center plane P in the regular hexagonal fuel assembly 1 coincides with the vertical split diagonal surface connecting between the diagonal ridgelines of the fuel assembly. In addition, here, the regular hexagonal fuel assembly 1 is rotated by 60 degrees around its axis by the inspected object holding mechanism 2 shown in FIG. 1 and attached to each facing surface of the fuel assembly 1 each time. It is possible to obtain the center point O ₁ with high accuracy by performing various measurements and calculating the center point obtained by each measurement so as to minimize the error by the least square method. Next, the method of inspecting the bending and twisting in the longitudinal direction of the fuel assembly 1 as the inspection object by the above-described inspection device will be described in order. That is, the largest cause of bending and twisting of the fuel assembly 1 is, as mentioned above, the entrance nozzle portion 11
If the fuel assembly 1 is bent or twisted due to a manufacturing error due to the welded joint between the fuel cell and the trumpet tube portion 12, the states are as shown in FIGS. 4 and 7, respectively. In each drawing, a regular hexagon shown by a solid line shows a cross section of the entrance nozzle portion 11, and a dotted line shows a cross sectional shape of the trumpet tube portion 12. The bending inspection method will be described first. As shown in FIG. 4, first, the weld nozzle 14 of the fuel assembly 1 is used as a boundary to define the entrance nozzle section 11 below the reference measurement range and the upper trumpet tube. First, the reference measurement position A is set in the entrance nozzle unit 11 with the section 12 as the target measurement range, and the third measurement is performed based on the output data of the displacement sensor 3 at the reference measurement position A.
The cross-section center point O ₁ is obtained by the method described in the figure, and a virtual center line indicated by the symbol C in FIG. 5 is set along the entire length of the fuel assembly 1 through the center point. The reference center line C is an axial center line on the assumption that the fuel assembly 1 is not bent. Next, the elevating drive mechanism 4 in FIG. 1 is operated to move the table 41 upward, and the displacement sensor 3 is positioned to face an arbitrary target measurement position B (FIG. 4) in the trumpet tube portion 12 of the fuel assembly 1. . Here, similarly to the previous time, the cross-sectional center point O ₂ of the fuel assembly 1 at the target measurement position B is obtained from the output data of the displacement sensor 3. The cross-sectional positions of the fuel assembly 1 at the reference measurement position A and the latter target measurement position B described above are the regular hexagons of the solid line and the dotted line shown in FIG. 6, and the center points of the solid line and the dotted line in this figure are shown. The relative deviation of O ₁ and O _{2 in} the cross-sectional direction represents the bending amount S of the target measurement position B with respect to the reference measurement position A of the fuel assembly 1. The bending amount S can be obtained by vector composition. A method for obtaining the bend of the fuel assembly 1 which is a regular hexagonal prismatic elongated body will be described with reference to FIG. 11 is the entrance nozzle portion of the fuel assembly 1, O ₁ is the center point of the cross section at the reference measurement position, 12 is the trumpet tube portion of the fuel assembly 1, and O ₂ is the center point of the cross section at the target measurement position. For each facing surface, the vectors S ₁ , S ₂ , and S ₃ of the relative displacement components with respect to the virtual center line in that direction are obtained, and first, the vector S
Combining ₁ and vector S ₂ , vector S ₂ and vector S
₃ and the combination of the vector S ₁ and the vector S ₃ . Furthermore, when the vector (S ₁ + S ₃ ), that is, O ₁ I is combined with the vector O ₁ G that is the combination of the vector (S ₁ + S ₂ ) and the vector (S ₂ + S ₃ ), the vector O ₁
H is obtained, which is 2 of the vector (S ₁ + S ₂ + S ₃ ).
Equivalent to double vector. Vector (S ₁ + S ₂ +
S ₃ ) is at the position 1/2 on the vector O ₁ H and is the vector O ₁ O ₂ . Cross-section center point O at target measurement position B
₂ is found in the center on the vector O ₁ H. In this way, the bending direction O ₁ O ₂ of O ₂ with respect to the center point O ₁ and the magnitude S of the bending amount can be obtained. Here, the degree of bending in the axial direction between the measurement positions A and B is schematically shown as a line D in FIG. The target measurement position B is set at several points along the trumpet tube portion 12 to obtain the direction and size of the bending amount at each position, and the measurement result is plotted by the inspection monitor unit 5 shown in FIG. By displaying and numerically outputting the numerical data, it is possible to determine whether the fuel assembly bends or not. Next, the twist inspection method will be described. In the case of this twist inspection, first, the reference measurement position A
(Fig. 7) is set and the fuel assembly 1 is set at this reference measurement position.
6 around the axis center of the object holding mechanism 2 (FIG. 1) to be inspected.
The output data of the displacement sensor 3 is arithmetically processed by the arithmetic control unit 5 (FIG. 2) by the method described in FIG. 3 while turning by 0 degree, and the center of the cross section of the fuel assembly shown by the solid line in FIG. A reference vertically-divided virtual center plane P ₁ connecting between the respective vertices of a regular hexagon through is set for each facing surface of the fuel assembly 1. Next, the displacement sensor 3 is moved upward to the trumpet tube portion 12,
Find the center plane P ₂ of the silo torsion connecting between output data of the displacement sensor at each opposing surface position in the target measuring position B of each vertex indicated by the dotted line, compared operation between the imaginary center plane P ₁ described above Then, the relative shift angles θ _{1 to} θ ₃ of the corresponding vertical split center planes are obtained. And this deviation angle θ
_The amount of twist between the reference measurement position A and the target measurement position B is calculated from the algebraic average of _{1 to} θ ₃ , and the measurement result is output to the monitor unit 6 as a figure and numerical data in the same manner as the bending amount inspection. Then, it is determined whether the fuel assembly is twisted. As is clear from the above description, for example, the inspection of bending and twisting of a prismatic elongated object to be inspected, which is a fuel assembly, is performed by holding the displacement sensor in a vertically held state and using a displacement sensor. The measurement operation is performed in a non-contact manner while moving up and down along. Therefore, compared with the conventional inspection method, since the inspected object is in the vertical standing posture, there is no bending in the axial direction of the inspected object due to gravity, and the error of the inspection accuracy due to the influence of gravity can be eliminated. . Further, since the displacement sensor measures the object to be inspected in a non-contact state, there is no risk of mechanical wear of the displacement sensor and surface damage or contamination of the object to be inspected. Since the sensors are arranged opposite to each other, even if there is an eccentricity error in the up-and-down drive path of the sensor, the error can be offset and compensated, and correct measurement can always be performed. Furthermore, a series of inspection operations can be performed by remote control, and even when a fuel assembly is targeted, there is an advantage that the inspection can be safely performed without risk of radiation exposure. Further, although the illustrated embodiment has been described with respect to the bending and twisting inspection of the object to be inspected for the regular hexagonal fuel assembly, the object to be inspected is not limited to the fuel assembly, and the rectangular column lengths of various shapes are used. Needless to say, the same can be applied to the scale body. In this case, the displacement sensor shown in FIG. 1 is installed so as to be movable back and forth with respect to the lifting table, and the amount of movement thereof is detected by an encoder, so that objects of various sizes can be inspected. It can be handled easily. Further, even at the reference measurement position, the lower entrance nozzle portion of the fuel assembly is set as the reference measurement position in the illustrated embodiment, but it is not limited to a general inspected object, and a long body By setting a reference measurement position at an arbitrary position on the axis of, it is possible to detect the relative bending and twist amount between this position and the displaced target measurement position.

【The invention's effect】

As described above, according to the present invention, the inspected object holding mechanism for supporting the inspected object, which is a polygonal prismatic elongated body, in an upright posture, and the non-contact type of the inspected object disposed laterally of the inspected object. A displacement sensor, an elevating and lowering drive mechanism for moving the displacement sensor up and down along an object to be inspected, and an arithmetic control unit for arithmetically processing output data of the displacement sensor. In the arithmetic control unit, in an upright holding state. An imaginary center line in the axial direction passing through the cross-sectional center point of the reference measurement position obtained from the output data of the displacement sensor measured for each opposing surface at the reference measurement position set on the axis of the object to be inspected, and the object to be measured. Vertically divided virtual center plane obtained from the output data of the displacement sensor at the reference measurement position set on the axis for each facing surface of the inspection object, and the inspected object at the target measurement position displaced from the reference measurement position The cross-sectional center point of the target measurement position obtained from the output data of the displacement sensor for each facing surface, and the virtual at the target measurement position obtained from the output data of the displacement sensor at the target measurement position displaced from the reference measurement position Comparing with the twist center plane corresponding to the center plane, the axial center between the reference measurement position and the target measurement position and the relative displacement of the center plane are calculated, and from the comparison calculation result, the length of the object to be inspected is calculated. By detecting the degree of bending and twisting along the direction, the degree of bending and twisting of the object to be inspected can be inspected in a non-contact manner and at the same time with high inspection accuracy. A high inspection device can be provided.

[Brief description of drawings]

FIG. 1 is a configuration layout diagram of an inspection device according to an embodiment of the present invention, FIG. 2 is a system diagram of an inspection system of the inspection device of FIG. 1, FIG. 3 is a diagram explaining the principle of the measuring method, and FIG. FIG. 5 is a side view and a cross-sectional view showing the bending state of the object to be inspected, FIG. 5 is a schematic diagram showing the bending state of FIG. 4, FIG. 6 is an explanatory diagram of a vector combining method for obtaining the bending amount, and FIG. FIG. 8 is a side view and a sectional view showing the twisted state of the object to be inspected, and FIG. 8 is an explanatory diagram for obtaining the twist amount. In each figure, 1: fuel assembly as an inspected object, 2: inspected object holding mechanism, 21: inspected object holding cylinder, 22: swivel drive unit, 23: encoder, 3, 31 to 34: displacement sensor ,
4: Lifting drive mechanism, 41: Lifting table, 42: Lifting feed screw mechanism, 43: Drive part, 44: Encoder, A: Reference measurement position, B: Target measurement position, C: Virtual center line,
O ₁ : cross-section center point of reference measurement position, O ₂ : cross-section center point of target measurement position, P ₁ : virtual center plane, P ₂ : twist center plane,
S: amount of bending, θ _{1 to} θ ₃ : twist angle.

Claims (3)

[Claims] 1. An apparatus for inspecting the degree of bending and twisting along a longitudinal direction of an object to be inspected, which is an elongated polygonal prism having an even numbered surface, and carries the object to be inspected in a standing posture. And a pair of non-contact type displacement sensors which are arranged in parallel on both sides of the object to be inspected and which are arranged in parallel with each other, and the displacement sensor is inspected. It has an elevating drive mechanism that moves up and down along the object, and an arithmetic control unit that arithmetically processes the output data of the displacement sensor, and in the arithmetic control unit, it is set on the axis of the object to be inspected in the upright holding state. A virtual center line in the axial direction passing through the center point of the cross section of the reference measurement position obtained from the output data of the displacement sensor measured for each facing surface at the reference measurement position, and on-axis for each facing surface of the inspected object Reference measurement position set to Of the vertical split virtual center plane obtained from the output data of the displacement sensor, and the target measurement position obtained from the output data of the displacement sensor for each facing surface of the inspected object at the target measurement position displaced from the reference measurement position The center point of the cross section and the twist center plane corresponding to the virtual center plane at the target measurement position obtained from the output data of the displacement sensor at the target measurement position displaced from the reference measurement position are compared with the reference measurement position. An average value of relative twist angles was calculated from the relative displacement of the axis center with respect to the target measurement position and the relative displacement of the center plane, and from the comparison calculation results along the longitudinal direction of the inspected object. An object bending / twisting inspection device characterized in that the degree of bending / twisting is detected. 2. The inspection device according to claim 1, wherein the displacement sensor is a capacitance type displacement sensor. 3. The inspection apparatus according to claim 1, wherein the inspected object holding mechanism is provided with a swivel mechanism for uprightly holding the inspected object and swiveling it about its axis center. Bending and twisting inspection device for characteristic objects.