JP4620895B2 - Inspection equipment such as pipe end welds - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection apparatus for inspecting a defect or a state of a pipe or a welded portion thereof using an ultrasonic probe.
[Prior art]
[0002]
As shown in FIG. 8, in the catalyst packed tube of the reactor and the heat transfer tube of the heat exchanger, the end portion of the tube 100 is fitted into the hole of the plate-like tube plate 101, and the peripheral edge 102 is welded. 101 is integrated.
However, if there is insufficient penetration or the like in the weld due to poor welding, problems such as leakage occur due to thermal stress in the process of use, and it is required to inspect for such defects in advance.
[0003]
Conventionally, an ultrasonic flaw detection test has been performed for inspection of defects in welds. In this test, a defect echo is identified from a reflected echo displayed on a display of an ultrasonic flaw detector, and a defect position and a defect size are estimated from a beam path length, an echo height, and the like of the echo.
However, as shown in FIG. 9, when the root portion 105 of the welded portion 103 at the end of the tube 100 is inspected by the ultrasonic probe 104, welding defects such as reflected echoes from the outer surface of the tube and insufficient penetration. It is impossible to separate and evaluate the reflected echo from the.
[0004]
Therefore, the inspection is carried out using the following method.
In FIG. 9, the route portion 105 that is likely to cause a welding defect 106 such as insufficient penetration or poor fusion is inspected in the welded portion 103. That is, in the welded portion 103 in which the tube 100 and the tube plate 101 are normally melted, the height of the reflected echo at the root boundary portion is almost halved relative to the height of the reflected echo from the tube outer surface 107. On the other hand, if there is a weld defect 106 in the root portion 105, a high reflection echo due to the defect 106 is displayed, so that the defect 106 can be found.
[0005]
[Problems to be solved by the invention]
In the inspection of the welded portion 103 by the ultrasonic flaw detector, as shown in FIG. 10, in the state where the surface of the probe 104 is in contact with the inner surface of the tube 100, the circumferential direction around the axis C of the tube 100 is performed. The probe 104 is rotated and scanned. When the operation at one place is completed, the probe is slightly shifted in the axial direction, and the probe is further rotated at that position to scan in the circumferential direction. In this way, the probe measures the distribution of reflected echoes for each position in the axial direction while slightly shifting in the axial direction, but when shifting in the axial direction, a caliper is used to measure 0.1-0. The probe 104 is rotated after being shifted in units of 05 mm and fixed at the shifted position.
However, the measurement using calipers in the tube 100 is very complicated, and there is a problem that accuracy is low and reproducibility is poor. Further, when the probe 104 is displaced in the axial direction, the probe 104 does not necessarily move in parallel with the axis, and the distance from the surface of the tube 100 may change.
[0006]
An object of the present invention is to provide an inspection device such as a pipe end welded portion that can easily and accurately determine the position of the probe in the axial direction and has high reproducibility of measurement.
Still another object of the present invention is to provide an inspection apparatus capable of accurately aligning the moving direction of the probe with the axial direction of the tube.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, an inspection apparatus such as a pipe end welded part of the present invention includes a housing installed at the end of a cylindrical pipe to be inspected, and is held so as not to move in the axial direction in the housing. A nut rotatably provided with respect to the housing, a motor for driving the nut to rotate, and a male screw threadedly engaged with the nut on an outer peripheral surface, and is rotatable and axially movable with respect to the housing. A drive shaft provided freely, a motor that rotationally drives the drive shaft, an ultrasonic probe attached to the drive shaft, a motor that rotationally drives the drive shaft, and a motor that rotationally drives the nut are synchronized. And a control mechanism for rotating the control mechanism .
[0008]
Thus, the present invention includes a nut that is provided so as not to move in the axial direction, a drive shaft that includes a male screw that is screwed to the nut, and a motor that rotationally drives the drive shaft. When the is rotated, the drive shaft is guided by the nut and screwed in the axial direction while rotating. Therefore, the probe provided on the drive shaft continuously scans the inner surface of the tube while drawing a spiral trajectory. In that case, since the rotation speed of the motor and the position of the probe correspond exactly, the measurement position can be determined accurately and the reproducibility is high. In addition, since the entire inner peripheral surface of the tube is continuously scanned, measurement is easy.
[0009]
Furthermore, the nut is provided rotatably with respect to the housing, and includes a motor that rotationally drives the nut, and a control mechanism that rotates the motor that rotationally drives the drive shaft and the motor that rotationally drives the nut in synchronization. Therefore , by rotating both motors in synchronization, the probe can be scanned in the circumferential direction while being set at the same height position in the axial direction. Furthermore, the probe can be displaced by an arbitrary dimension in the axial direction by stopping the motor of the drive shaft and rotating only the second motor. Thereby, the entire inside of the tube can be scanned at an arbitrary pitch. Further, by rotating both motors at different rotational speeds at the same time, it is possible to scan spirally at a fine pitch or a coarse pitch.
[0010]
Furthermore, in the inspection apparatus according to the present invention, a first support member inserted into another pipe separated from the pipe to be inspected in parallel with the axis of the housing, and a first shaft connecting the drive shaft and the first support tool. And a second support disposed on a second line intersecting with the first line, and the distance between the drive shaft and the first support and the distance between the drive shaft and the second support are adjustable. What is done is preferable. This inspection apparatus inserts a first support tool and a second support tool into two pipes separated from the pipe to be inspected, respectively, so that the axis of the drive shaft is aligned with the axis of the pipe to be measured. Can be adjusted accurately.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a sectional view showing an outline of the entire inspection apparatus according to this embodiment. In FIG. 1, reference numeral 1 denotes a housing, and a drive shaft 3 is accommodated in the housing 1 via a drive mechanism 2 so as to be rotatable and axially movable. A first motor M 1 and a second motor M 2 for driving the drive shaft 3 are attached to the housing 1. A sensor unit 4 is provided at the lower end of the drive shaft 3. The sensor unit 4 is a columnar member that is inserted into the tube 5 to be measured. The housing 1 is held by a holder 6 on a tube 5a adjacent to the tube 5 to be inspected or on a tube plate 7 welded to the ends thereof. A holding plate 8 is attached to the housing 1, and a support 9 that is inserted into the separated pipe 5 b is attached to the holding plate 8.
[0012]
FIG. 2 shows an enlarged view of the drive mechanism 2 of the inspection apparatus 10 shown in FIG. The housing 1 is divided into a cylindrical lower housing 11 and a second housing 12 concentrically arranged on the upper portion. A plate-like lower base 13 is attached to the upper end of the lower housing 11 with screws 14, and a plate-like upper base 15 is attached to the lower end of the upper housing 12 with screws 16. The lower base 13 and the upper base 15 are fixed to each other with a plurality of pipe-like spacers 17 interposed therebetween and screws 17a passing through the spacers.
[0013]
Further, a cylindrical nut holder 18 is rotatably held inside the upper end of the lower housing 11 via a bearing 19. A nut 20 is fitted inside the nut holder 18 and fixed by a key 21 so as not to rotate. On the outer periphery of the drive shaft 3, a male screw 22 that is screwed with the nut 20 is formed. The female screw of the nut 20 and the male screw 22 of the drive shaft 3 are preferably trapezoidal screws that can withstand axial loads, for example. Ball screws may be used for the male screw 22 and the female screw. Reference numeral 23 denotes a retaining ring that holds the nut 20 and stops its axial movement.
[0014]
A flange 24 is provided on the outer periphery of the nut holder 18, and a ring-shaped first gear 25 is concentrically fixed to the flange 24 by a screw 24 a. The first motor M1 is attached to the lower base 13 with screws 26, and a first pinion 27 is fixed to the output shaft of the first motor M1. The first pinion 27 meshes with the first gear 25. The speed reducer provided between the first motor M1 and the output shaft is preferably a self-restraining speed reducer such as a worm speed reducer.
[0015]
A bush holder 32 is rotatably accommodated in the upper housing 12 via a bearing 31. The lower end of the bush holder 32 is supported by an outer ring of a ball bearing 33 attached to the outer periphery of the upper end of the nut holder 16. A cylindrical spline bush (spline nut) 34 is fitted inside the bush holder 32 and fixed by a key 35 so as not to rotate. The lower end of the spline bush 34 is supported by a flange 36 that protrudes inward from the lower end of the bush holder 32.
[0016]
A spline 37 that meshes with the spline bush 34 and transmits torque while allowing axial sliding is fixed to a portion corresponding to the spline bush 34 of the drive shaft 2. The lower end of the spline 37 is engaged with and supported by a step formed on the drive shaft 3. Note that the spline 37 may be formed integrally with the drive shaft 3. Ball splines may be adopted as the spline 37 and the spline bush 34. In addition, other transmission means such as a slide key can be adopted as long as it can transmit torque while allowing the drive shaft to move in the axial direction.
[0017]
A flange 38 is provided on the outer periphery near the lower part of the bush holder 32, and a ring-shaped second gear 39 is fixed to the flange 38. The second gear 39 meshes with a second pinion 41 attached to the output shaft of the second motor M2 with a screw 40. The second motor M2 is fixed to the upper base 15 with screws 42. It is preferable that the speed reducer between the second motor M2 and the output shaft is also a self-restraining type.
[0018]
4 (a), 4 (b), and 4 (c) are schematic perspective views for explaining the operation of the drive mechanism of FIG. Hereinafter, the operation of the drive mechanism 2 will be described with reference to FIGS. 2 and 4 (a), 4 (b), and 4 (c).
[Helix motion] With the lower first motor M1 in FIG. 2 stopped, the upper second motor M2 is rotated in the direction of arrow J1 (the rotation direction of the output shaft; the same applies hereinafter).
Then, the second pinion 41 rotates in the same direction, and the second gear 39 engaged therewith rotates in the reverse arrow J2 direction. The bush holder 32 and the spline bush 34 also rotate in the direction of arrow J2. Therefore, the drive shaft 3 also rotates in the direction of arrow J2. At that time, the first motor M1 is stopped and the nut 20 is stopped, so that the drive shaft 3 is screwed downward along the female screw of the nut 20. That is, it descends while drawing a spiral trajectory (see FIG. 4A). The pitch of the helix is the same as the screw pitch of the nut 20 and is lowered by one pitch (arrow Pd) with respect to one rotation of the drive shaft 3. When the second motor M2 rotates in the reverse direction, the second motor M2 moves up while drawing a spiral contrary to the above.
[0019]
[Straight motion] When the first motor M1 is rotated in the direction of the arrow K1 with the second motor M2 stopped, the first pinion 27 rotates in the same direction, and the first gear 25 meshed with the first pinion 27 is reversed. Rotate in the direction (arrow K2 direction). The nut holder 18 and the nut 20 also rotate in the direction of the arrow K2. And since the 2nd motor M2 has stopped, the drive shaft 3 cannot rotate by meshing | engagement of the spline 37 and the spline bush 34, but can move only to an up-down direction. Therefore, as the nut 20 rotates, the drive shaft 3 rises linearly (see FIG. 4B). The speed is equivalent to one pitch of the screw (arrow Pu) every time the nut 20 rotates once. When the first motor M1 rotates in the reverse direction, it descends linearly, contrary to the above.
[0020]
[Simple Rotation] When the first motor M1 is rotated in the direction of the arrow K1 and the second motor M2 is rotated in the direction of the arrow J1 at the same speed (as viewed on the output shaft), Combined with the straight ascent, it rotates while maintaining the original position in the axial direction as shown in FIG. As can be seen from FIG. 4 (c), since the drive shaft 3 and the nut 20 rotate so to speak, it is considered that there is no relative movement of the nut 20 and the drive shaft 3, and therefore neither rises nor lowers. You can also. By adopting the spiral motion, the straight motion, and the simple rotational motion alone, or in combination with each other at the same time or sequentially, various scanning states of the sensor unit 4 to be described later can be determined.
[0021]
The inside of the drive shaft 3 in FIG. 2 is hollow, and an electric wire 44 extending to the sensor unit 4 is accommodated therein. A cylindrical connector holder 45 is attached to the upper end of the drive shaft 3, and a connector 46 connected to the end of the electric wire 44 is accommodated therein. FIG. 2 shows a state in which the mating connector 47 is attached to the connector 45. The mating connector 47 is attached to the connector holder 45 with a screw cap 48. The mating connector 47 is connected to the amplifier of the ultrasonic probe.
[0022]
A proximity sensor (proximity switch) 50 for detecting the spline 37 and the connector holder 45 is attached to the upper housing 12 and the bracket 49 attached to the upper housing 12. These proximity sensors 50 are used for detecting the upper and lower ends of the vertical stroke of the drive shaft 3 and stopping the motors M1 and M2.
[0023]
As shown in the lower part of FIG. 2, a downward step portion 52 is formed in the middle of the drive shaft 3, and the upper surface of the thrust bearing 53 is engaged with the step portion 52. The thrust bearing 54 is urged upward by a spring 56 via a spring receiver 55. That is, the weight of the drive shaft 3 is balanced by the spring 56 so as not to prevent rotation. In this embodiment, the spring 56 is a compression coil spring.
[0024]
FIG. 3 shows an enlarged view of the lower portion of the drive shaft 3, the sensor section 4 and the holder 6. As shown in the upper part of FIG. 3, the lower end of the spring 56 is supported by a flange portion of a cylindrical spring receiver 58 placed on the bottom 57 of the lower housing 11. The spring receiver 58 functions to align the center of the spring 56 and also serves as a stopper when the above-described upper spring receiver 55 is lowered by mistake.
[0025]
The sensor unit 4 is a cylindrical member and is detachably connected to the drive shaft 3 by a split coupling member 60. Thereby, the suitable sensor part 4 can be selected with respect to the pipe | tube from which a pipe diameter differs. A recess 61 is formed in the side surface of the sensor unit 4, and an ultrasonic probe 62 is arranged and fixed in the diametrical direction therein. The tip of an ultrasonic probe (hereinafter simply referred to as a probe) 62 is flush with or slightly protruding from the surface of the sensor unit 4 and is in sliding contact with the inner surface of the tube 5 to be measured. Yes.
[0026]
FIGS. 5A, 5B, and 5C are schematic development views each showing a scanning state by the inspection apparatus of FIG. The probe 62 configured as described above can scan the cylindrical inner surface of the tube 5 in accordance with the operation mode of the drive mechanism 3 described above.
[Spiral trajectory scanning]
By rotating only the second motor M2 for the drive shaft 3 of the drive mechanism 3 in the direction of the arrow J1 in FIG. 4, the drive shaft can be lowered while rotating. As a result, the probe 62 descends in a spiral manner as shown in FIG. Therefore, as shown in the development view of FIG. 5A, the inner surface of the tube 5 can be continuously scanned in an oblique direction at the same pitch as the screw pitch.
[0027]
Next, when the second motor M2 is rotated in the direction of the arrow J1 and the first motor M1 is rotated in the direction of the arrow K1 at a lower speed (for example, 1/2) than the second motor M2, the rotation of the drive shaft 3 is performed. While descending, the drive shaft 3 ascends at half the descending speed based on the rotation of the nut 20. Therefore, as shown in FIG. 5B, the inner surface of the tube 5 can be scanned in an oblique direction at a pitch that is ½ of the screw pitch. By controlling the speeds of the second motor M2 and the first motor M1 in this way, the drive shaft 3 can be spiraled at an arbitrary pitch, and a wide range in the tube 5 can be continuously moved at an arbitrary pitch. You can scan.
[0028]
[Circumferential scanning]
When intensively inspecting a site where defects such as welding are likely to occur, the first motor M1 is rotated in the direction of the arrow J1 and the second motor M2 is rotated in the direction of the arrow K1 at the same speed. As a result, as described in FIG. 4C, the drive shaft 3 rotates at the same height, and can be scanned in the circumferential direction at the same height as shown in FIG. 5C.
[0029]
Furthermore, when scanning the position of a different height to the circumferential direction, only the 2nd motor M is rotated and a linear motion (refer FIG.4 (b)) is given. Next, the first motor M1 and the second motor M2 are simultaneously rotated again to perform circumferential scanning. The pitch of the first circumferential scan and the second circumferential scan is arbitrary because it can be determined by the rotation angle of the nut 20 during linear movement. As described above, various scanning states can be obtained. However, in order to obtain a desired scanning state, it is necessary to accurately control the rotational speeds of the first motor M1 and the second motor M2. Therefore, it is preferable to use a motor that can accurately control the rotation angle, such as a stepping motor.
[0030]
FIG. 6 is a plan view of the inspection apparatus 10 of FIG. A handle 64 protruding in the radial direction is attached to the upper base 15 of the inspection apparatus 10. Holding the handle 64 is convenient when carrying the inspection apparatus 10, inserting a sensor part into the tube to be measured, or pulling it out.
[0031]
FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 1, and shows the positional relationship between the axis C of the drive shaft and the first support 9a and the second support 9b. The holding plate 8 has a ring-shaped base portion 66 disposed around the lower housing 11 and an arm 67 protruding outward from the base portion in the radial direction. As shown in FIG. 3, the ring-shaped base 66 is fixed to the lower flange of the lower housing 11 by a pressing ring 68 and a screw 69. As shown in FIG. 7, the arm 67 is provided with a long hole 70, and the upper ends of the first support 9a and the second support 9b are attached to the long hole.
[0032]
In this embodiment, as shown in FIG. 3, a flange 71 that contacts the lower surface of the arm 67 and a convex portion 72 that fits into the long hole 70 are provided at the upper end of each support 9. Thereby, each support tool 9 is fixed to the arm 67 using the washer 73 and the screw 74 provided on the upper surface side of the arm 67 while adjusting the distance from the axis C of the drive shaft. In the present embodiment, the angle of the two arms 67 is set to 60 degrees in accordance with the arrangement state of the tubes to be measured. However, other angles may be used and the angle can be adjusted. A plurality of imaginary lines R in FIG. 7 intersect with each other indicate the arrangement state of the center positions of the tubes.
[0033]
The two support members 67 are parallel to the drive shaft 3 as shown in FIG. 3, and are inserted into the two tubes 5 b apart from the tube 5 to be measured. The parallelism with the pipe 5 to be measured can be made accurate. A cylinder 75 is detachably attached to the support 9 by screws 76 so that it can be used for pipes having different diameters.
[0034]
【The invention's effect】
According to the present invention, the nut and the drive shaft are screw-coupled, and the drive shaft can be rotationally driven by the motor. Therefore, by rotating the drive shaft by the motor, the probe is continuously spiraled by the probe. Can be scanned.
When a motor that rotates the nut is provided in addition to the motor that rotates the drive shaft, the probe is connected to the tube by rotating the motor that rotates the drive shaft and the motor that rotates the nut in synchronization. It is possible to scan in the circumferential direction at the same position in the axial direction. Further, by rotating the nut motor slower (or faster) than the drive shaft motor, it is possible to scan spirally at a pitch (or coarser pitch) that is finer than the screw pitch.
[0035]
When the first support member and the second support member are provided in parallel in the housing that supports the drive shaft, the drive shaft is measured by inserting the support members into two tubes that are separated from the tube to be measured. Can be accurately positioned relative to the tube.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an overview of an entire inspection apparatus according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of an upper portion (drive mechanism) of the inspection apparatus shown in FIG.
3 is an enlarged cross-sectional view of a lower part (a sensor unit or the like) of the inspection apparatus shown in FIG.
4A, 4B, and 4C are schematic perspective views for explaining the operation of the drive mechanism shown in FIG.
FIGS. 5A, 5B, and 5C are schematic development views each showing a scanning state by the inspection apparatus of FIG.
6 is a plan view of the inspection apparatus of FIG. 1. FIG.
7 is a cross-sectional view taken along line VII-VII in FIG.
FIG. 8 is a cross-sectional view showing an attached state of a catalyst filling tube or a heat exchanger tube for heat exchanger.
FIG. 9 is an explanatory view showing a method for inspecting a root portion in a welded portion where pipes are welded.
10 is a cross-sectional view showing an inspection state by the ultrasonic probe shown in FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Drive mechanism, 3 ... Drive shaft, 4 ... Sensor part, 5 ... Pipe, 6 ... Holder, 7 ... Tube plate, 8 ... Holding plate, 9, 9a, 9b ... Support tool, 10 ... Inspection Device: 11 ... Lower housing, 12 ... Upper housing, 18 ... Nut holder, 20 ... Nut, 22 ... Male screw, M1 ... First motor, M2 ... Second motor, 25 ... First gear, 27 ... First pinion, 32 ... Bush holder, 34 ... Spline bush, 37 ... Spline, 39 ... Second gear, 41 ... Second pinion, 62 ... Ultrasonic probe

Claims (2)

A housing installed at the end of a cylindrical tube to be inspected;
A nut that is held in the housing so as not to move in the axial direction, and is provided rotatably with respect to the housing ;
A motor that rotationally drives the nut;
A drive shaft having a male screw threadedly engaged with the nut on the outer peripheral surface and provided rotatably with respect to the housing and axially movable;
A motor that rotationally drives the drive shaft;
An ultrasonic probe attached to the drive shaft ;
A control mechanism for rotating the motor driving the drive shaft and the motor driving the nut synchronously ;
Inspection equipment such as pipe end welds.   On the second line intersecting the first line connecting the drive shaft and the first support, and the first support inserted into another pipe away from the pipe to be inspected in parallel with the axis of the housing 2. The inspection according to claim 1, further comprising: a second support tool disposed on the first support tool, wherein the distance between the drive shaft and the first support tool and the distance between the drive shaft and the second support tool are adjustable. apparatus.

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