JP2989153B2 - Straightness inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting the straightness of a long cylindrical object to be inspected made of metal. The present invention relates to a limit gauge type inspection device which arranges and passes an object to be inspected while rotating the same, and electrically inspects the presence or absence of contact between the upper surface plate and the object to inspect the straightness. . The inspection apparatus is not particularly limited, but is useful for straightness inspection of, for example, a fuel rod for a nuclear reactor.

[0002]

2. Description of the Related Art For example, fuel rods of a new type of converter are filled with a required nuclear fuel material or the like in a metal-made long cylindrical cladding tube having a diameter of about several tens of mm and a length of about 4 m. And the lower end plug is welded and sealed. Extremely accurate straightness is required for this type of fuel rod, and its specifications are very strict. More specifically, the straightness is specified to be 0.25 mm or less.

A conventional straightness inspection has been performed using a surface plate 90 and a gap gauge 92 as shown in FIG. In the figure, A is a front view, and B is a side view. First, the test object 10 is set on the surface plate 90 and rolled. If it is curved, when both ends of the test object 10 are brought into contact with the surface plate 90,
The curved part rises. Therefore, when the curved portion of the test object 10 rises and the gap with the surface plate 90 becomes maximum,
The straightness is obtained by measuring the gap with the gap gauge 92.

[0004]

However, when the object to be inspected is the fuel rod of the new type converter described above, since the straightness specification is very severe, automation is considered difficult from the viewpoint of measurement accuracy. Was. For this reason, the measurement by the above-described inspection apparatus has been performed manually, but has the following problems. In the case of a long object to be inspected, it is necessary to arrange two or three inspectors in front of the platen in order to increase work efficiency. The measured values vary greatly depending on the skill and ability of the inspector. When the object to be inspected is a fuel rod for a nuclear reactor, radiation exposure is inevitable because the curved portion is visually checked and measured.

[0005] It is an object of the present invention to provide a straightness inspection apparatus which can automate the measurement of straightness, thereby increasing the working efficiency and improving the inspection accuracy by suppressing variations in measured values. . Another object of the present invention is to provide a straightness inspection apparatus capable of reducing the exposure of workers when the inspection object is a fuel rod for a nuclear reactor.

[0006]

SUMMARY OF THE INVENTION The present invention is a limit gauge type device for inspecting the straightness of a long cylindrical object to be inspected made of metal. In principle, this inspection apparatus is arranged such that the surfaces to be used face each other at an interval g (= d + t) obtained by adding the allowable straightness value t to the outer diameter d of the inspection object 10, as shown in FIG. The lower surface plate 12 and the upper surface plate 14 which have been
Voltage applying means 16 for applying a weak voltage between the zero and upper platen 14, conduction detecting means 18 for detecting the presence / absence of conduction between the two, and the test object 10 by using the upper platen 14 and the lower platen 12 And a device 20 for pushing an object to be inspected while rotating between them. Needless to say, the width of the upper stool 14 is set to be equal to or longer than the circumference of the test object 10.

The device under test 10 is passed through the gap between the lower surface plate 12 and the upper surface plate 14 in the direction of the arrow while rotating from the position a to the position b. If a weak voltage is applied in advance between the test object 10 and the upper platen by the voltage applying means 16, if the test object 10 bends greatly, the test object 1
When the zero curved portion comes into contact with the upper surface plate 14, it becomes an electrically conductive state and a weak current flows. The weak current can be detected by the conduction detecting means 18. In this way, it is possible to automatically determine whether the straightness is equal to or greater than the allowable value based on the presence or absence of electrical conduction.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, the upper platen can be lifted and lowered in a double-sided structure by jacks at both ends, so that the lower platen and the upper platen can be moved so as to be able to cope with various changes in the outside diameter or allowable value of the test object. Can be freely adjusted. The test object pushing device includes a transport member having a slot portion in which the test object is loosely fitted in a plate-like body thinner than the outer diameter of the test object, and a state in which the test object is loosely fitted in the slot portion. And a drive mechanism for inserting the transport member between the lower surface plate and the upper surface plate. Then, it is preferable to apply a weak voltage between the transport member and the upper platen. Inspection object receiving devices are provided on both sides of the lower platen, respectively. The inspection object receiving device includes a plurality of lifters that can move up and down in conjunction with each other,
A test object receiving member having an escape hole that penetrates each lifter when the test object is lifted and lowered, one of the test object receiving devices is a receiving side, the other is a transfer side, and the receiving side is a plurality of single lifters. The test object supplied from above is supported at the time of ascending, and received by the test object receiving member by descending,
The transfer side has a structure in which the test object in the test object receiving member is supported and lifted and transferred by raising the plurality of single lifters.

[0009]

FIG. 2 is an overall configuration diagram showing one embodiment of a straightness inspection apparatus according to the present invention, wherein A is a front view and B is a side view. A rectangular parallelepiped lower platen 12 is placed on the floor. In addition, a square frame base 22 is installed around the lower surface plate 12 on the floor, and base blocks 24 are erected on both ends of the base 22, and the upper surface plate 14 is placed on both base blocks 24. Straddle. The upper platen 14 is located above the lower platen 12 with a small space therebetween, and is arranged such that the upper surface of the lower platen 12 and the lower surface of the upper platen 14 face each other.
In addition, a concave portion 26 is provided in an upper portion of the base block 24,
A jack (leveling block) 28 is incorporated in the concave portion 26, and the upper surface plate 14 is supported by the jack 28.

FIG. 3 shows an example of their actual structure. The lower lapping plate 12 is a precision lapping plate having a flatness equivalent to that of JIS-0 class, and is made of a stone material to reduce deformation with respect to an installation environment temperature and improve measurement accuracy.
The upper surface plate 14 is a precision surface plate having the same flatness as the lower surface plate 12, and is made of stainless steel in order to obtain electrical continuity with the object to be inspected and to prevent rust. Also, basically, the whole is formed into an I-beam structure, and laterally extending portions 14a are provided at appropriate intervals so as to be continuous with upper and lower flat plate portions, and holes 14b are formed between the extending portions 14a. The overall weight is reduced and the rigidity is increased, making it difficult to deform when supporting at both ends. The base block 24 is made of cast iron and has a high rigidity structure. The surface on which the upper platen is mounted and the surface fixed to the base are machined so that the parallelism is within 5 μm. The upper platen 12 can be moved up and down by mounting the jack 28 in the concave portion 26 formed at the upper portion as described above, and by inserting spacers 30 on both sides thereof, the dimension between the upper and lower platens can be changed. is there.

The jack 28 is a well-known leveling block as shown in FIG. 4, and is composed of two wedge-shaped tables 34a and 34b which are vertically assembled by turning a bolt 32.
Is a device that can move relatively to adjust the height. For example, when the bolt 32 is rotated in the direction of the arrow r, the upper table 34a is lifted in the direction of the arrow f while being drawn, as shown by the arrow u. When the bolt 32 is rotated in the opposite direction, the upper table 34a is lowered. This jack 2
The upper platen 12 is mounted on the upper recesses 26 of both base blocks 24, thereby supporting the upper platen 12 at both ends. By operating the jack 28, the position of the upper platen 12 in the vertical direction is adjusted. And the upper surface of the base block 24 and the upper surface plate 1
By inserting a spacer 30 having an appropriate thickness between the upper surface plate 4 and the lower surface plate 4, the distance between the opposing surfaces of the lower surface plate 12 and the upper surface plate 14 is set to a value obtained by adding the allowable straightness value to the outer diameter of the test object.

Returning to FIG. 2, between the lower platen 12 and the upper platen 14, there is provided a device 40 for pushing the object while rotating the object while rotating. The inspection object pushing device 40 includes a transport member 42 that passes between the lower surface plate 12 and the upper surface plate 14, and a drive mechanism 44 that moves the transport member 42. FIG. 5 shows an example of the transport member 42. This is a structure in which a slot portion 48 into which the test object 10 is loosely fitted is formed in a stainless steel plate 46 slightly thinner than the outer diameter of the test object 10. Accordingly, the test object 10 in the slot portion 48 is pushed and passes between the lower surface plate 12 and the upper surface plate 14 while rotating. Therefore, the drive mechanisms 44 located at both ends of the transport member 42 may be of any type as long as the transport member 42 can reciprocate from one side of the lower platen 12 to the other side.

Although not shown, this embodiment also includes the same voltage applying means and conduction detecting means as those shown in the principle diagram of FIG. The voltage applying means applies a weak voltage between the test object and the upper surface plate. However, in this case, a weak voltage is applied between the upper platen and the transport member so that the test object can be continuously and automatically measured. Therefore, as shown in FIG. 6, an electric insulating material 50 is sandwiched between the lower portions of both drive mechanisms 44 shown in FIG. . Since the lower surface plate 12 is made of stone, electrical insulation is maintained even when it comes into contact with it. When the test object 10 is stored in the slot portion 48 of the conveying member 42 and conveyed, the test object 1
Since the transport member 42 is in contact with 0, it is electrically conductive.
In particular, in the case where the straightness of the test object 10 is low and the test member 10 comes into contact with the upper surface plate 14, the transfer member 42 always contacts the test object 10 because the resistance for conveyance increases, and the test object 10 is electrically connected. It becomes conductive. In this case, the drive mechanism 44 is configured to automatically stop upon receiving a signal indicating the occurrence of electrical conduction.

Returning to FIG. 2, the inspection object receiving devices 60 are provided on both sides of the lower platen 12, respectively. The inspection object receiving device 60 includes a plurality of single lifters 62 that can be moved up and down in synchronization with each other, and an inspection object receiving member 66 having a clearance hole 64 that penetrates when each of the single lifters 62 moves up and down. Each one
The upper end of the lifter 62 has a notch structure such as a V-shape or a U-shape, and the test object having a circular cross section is accommodated in the notch. One side of the lower platen (for example, B in FIG. 2)
Is the receiving side, and the opposite side (the right side of B in FIG. 2) is the receiving side. The receiving side supports the test object supplied from above when the plurality of single lifters 62 are raised, and receives the test object with the test object receiving member 66 by descending. In this structure, the test object in the test object receiving member 66 is supported at both ends and lifted and delivered. The single lifters 62 are arranged at appropriate, substantially uniform intervals (for example, about eight for a test object having a length of about 4 m) in order to support a long test object without causing bending deformation. The lower end may be erected on a common horizontal bar member (not shown) to move the horizontal bar member up and down. It goes without saying that the relief holes 64 formed in the inspection object receiving member 66 are also provided in accordance with the installation interval of each single lifter 62.

FIG. 7 shows a measurement procedure performed by the straightness inspection apparatus thus configured. A is a state before inspection. When the straightness measurement is performed where the outside diameter of the test object is dmm and the straightness tolerance is tmm, the distance gmm between the lower surface plate 12 and the upper surface plate 14 is expressed as g =
(D + t) is set. Specifically, while measuring with a length measuring instrument such as a flow rate air micrometer, the level of the upper stool 14 is adjusted with a jack, and a spacer is inserted between the upper stool 14 and the base block. The distance g between the lower surface plate 12 and the upper surface plate 14 is determined.

Next, as shown in B, the transport member 42 of the device for pushing the device to be inspected is placed in a state of overlapping with the device receiving member 66 of the device for receiving the device to be inspected on the receiving side (left hand side in the drawing). This is an initial state. Then, each lifter 62 of the receiving device of the inspection object receiving side is simultaneously raised, and the inspection object 10 is received by the V-shaped notch at the upper end thereof.
For example, when the object to be inspected is a fuel rod for a nuclear reactor, the fuel rod for a nuclear reactor is received from a fuel rod handling device. Each one
When the lifter 62 is lowered, the inspection object 10 is received by the inspection object receiving member 66 as shown in C, and fits in the slot portion of the transport member 42 of the inspection object pushing device. Since the thickness of the transport member 42 is smaller than the outer diameter of the inspection object 10, a part of the inspection object 10 slightly protrudes from the upper surface of the transport member 42.

In this state, the transport member 42 containing the test object 10 is advanced by the driving mechanism 44, and passes through the gap between the lower stool 12 and the upper stool 14 (see D). 8 to 24 V AC between the pushing device and the upper platen 14 before the upper platen 14
The transfer member 42 is moved forward by passing the upper platen 14 by applying a voltage of the order of magnitude. Instead of applying an AC voltage, a configuration in which a DC voltage is applied may be used. If the straightness of the test object 10 is equal to or larger than the allowable value, the gap g between the lower surface plate 12 and the upper surface plate 14 is set to (d + t). Then, a current flows between the test object 10 and the upper surface plate 14, and the conduction detecting means reports that the straightness exceeds the allowable value. The notification means may be, for example, lighting a lamp or sounding a buzzer. At the same time as the notification means operates, the drive mechanism 44 automatically stops to prevent the inspection object 10 from being damaged or deformed by an excessive transport operation. If the straightness of the test object 10 is within the allowable range, the test object does not contact the upper surface plate 14, and no current flows between the test object 10 and the upper surface plate 14.

When the straightness of the test object 10 remains within the allowable range, that is, when the measurement is completed without operating the notifying means,
As shown in E, the transport member 42 is in a state of overlapping with the inspection object receiving member 66 of the inspection object receiving device on the delivery side (the right hand side in the drawing). When each one lifter 62 of the receiving device of the inspection object on the delivery side is simultaneously raised, the inspection object 10 can be received by the V-shaped notch at the upper end thereof (see F).
The test object thus measured is delivered to the next step.

The straightness inspection of the fuel rod (outer diameter 14.5 mm, total length 4120 mm, allowable straightness 0.25 mm) of the new converter was conducted using the prototype straightness inspection apparatus. As a result, the upper and lower platen gap variation range was ± 0.028 mm, and the current detection accuracy was ± 0.002 mm. This is a sufficiently small value with respect to the allowable value, and it was confirmed that it was useful as an inspection device. The apparatus of the present invention can be applied to not only the straightness inspection of a fuel rod for a nuclear reactor, but also the straightness inspection of a cladding tube for a fuel rod, and the straightness inspection of a metal round bar or cylindrical member used in other technical fields. .

[0020]

As described above, according to the present invention, the upper and lower platens are arranged so that the surfaces to be used face each other, and the object to be inspected is rotated and passed between the surfaces. Is a limit gauge type straightness inspection device that is configured to electrically detect electrical signals, which enables automatic inspection, saves labor for measurement except for inspection preparation work such as calibration, and implements measurement work. As a result, the dispersion of the measured values is reduced, and the inspection accuracy can be improved. In particular, the present apparatus can contribute to the reduction of radiation exposure of workers since the straightness of a fuel rod for a nuclear reactor can be automatically inspected.

Further, in the present invention, if the upper platen can be raised and lowered by a jack, the dimensions between the upper and lower platens can be changed, so that the outer diameter of the test object and the allowable straightness can be changed. It is possible to perform straightness inspection and sorting according to them.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of a straightness inspection apparatus according to the present invention.

FIG. 2 is an explanatory view showing an embodiment of a straightness inspection apparatus according to the present invention.

FIG. 3 is an explanatory view showing a structural example of upper and lower platens.

FIG. 4 is a perspective view showing an example of a jack used in the present invention.

FIG. 5 is a plan view showing an example of a transport member of the device for pushing an object to be inspected used in the present invention.

FIG. 6 is a sectional view showing an electrical insulation structure of the device for pushing an object to be inspected used in the present invention.

FIG. 7 is an explanatory diagram of the operation of the device of the present invention.

FIG. 8 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Inspection object 12 Lower surface plate 14 Upper surface plate 16 Voltage application means 18 Conduction detection means 20 Inspection object pushing means

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Claims (4)

(57) [Claims] 1. A limit gauge type device for inspecting the straightness of a long cylindrical object to be inspected made of metal, wherein a surface to be used is spaced at an interval obtained by adding an allowable straightness value to an outer diameter of the inspected object. A lower surface plate and an upper surface plate disposed so as to face each other, a voltage application unit that applies a weak voltage between the test object and the upper surface plate, and a conduction detection unit that detects whether there is electrical conduction between the two. An inspection object pushing device that passes the inspection object while rotating between the upper surface plate and the lower surface plate, and determines whether the straightness is equal to or more than an allowable value depending on the presence or absence of electrical conduction. Characteristic straightness inspection device. 2. The upper platen can be raised and lowered in a double-sided structure by jacks at both ends, and the distance between the lower platen and the upper platen can be freely adjusted so as to be able to cope with various changes in the outside diameter of the object to be inspected or allowable values. The straightness inspection device according to claim 1, wherein the straightness inspection device is enabled. 3. A device for pushing an object to be inspected, comprising: a conveying member having a slot portion in which the object to be inspected is loosely fitted in a plate-like body thinner than the outer diameter of the object to be inspected; The straightness inspection apparatus according to claim 1 or 2, further comprising a drive mechanism that allows the transport member to pass between the lower surface plate and the upper surface plate in a loosely fitted state. 4. A test object receiving device is provided on both sides of the lower platen. The test object receiving devices each include a plurality of lifters which can be simultaneously moved up and down, and a relief which penetrates when each of the lifters is moved up and down. An inspection object receiving member having a hole, one of the inspection object receiving devices is a receiving side and the other is a transfer side, and the receiving side is supplied from above when the plurality of single lifters are raised. The inspection object is supported, received by the inspection object receiving member by descending, and the delivery side is configured to support the inspection object in the inspection object receiving member by lifting the plurality of single lifters, and to lift and deliver the inspection object. Item 5. A straightness inspection device according to items 1 to 3.