Device for ultrasonic flaw detection in rotary electric machine

Abstract

The present invention is constituted from a holding mechanism (4) that is insertable in a gap between a rotor (41) and a stator (31) of a rotary electric machine and in which an ultrasonic probe (9) is easily replaced and changed, a three-dimensional drive mechanism (2) that follows the curvature and slope of a surface to be inspected, an elastic mechanism (3) for performing pressing force adjustment of the ultrasonic probe (9), and a support structure (5) for carrying out of a flaw detection operation by an inspector (51). The three-dimensional drive mechanism (2) causes the ultrasonic probe (9) to smoothly follow the curvature and slope of the surface to be inspected, and it is thereby possible to finely adjust the pressing force of the ultrasonic probe (9) and cause the ultrasonic probe (9) to scan smoothly over the surface to be inspected, and to reproduce a fine pressing force adjustment performed by a trained inspector (51).

Description

Ultrasonic flaw detection equipment for rotating electrical machines

[0001] The present application relates to an ultrasonic flaw detector for a rotating electrical machine.

[0002] In the past, the mainstream maintenance and inspection of rotating electrical machines involved pulling the rotor out of the stator and disassembling it to inspect the wedges, retaining rings, and other components. However, the process of pulling the rotor out required long shutdown periods and high costs. Therefore, methods for inspecting rotating electrical machines without pulling the rotor out of the stator have been proposed. For example, Patent Document 1 discloses a probe-integrated ultrasonic flaw detection device and ultrasonic flaw detection method that incorporates an ultrasonic probe and a probe drive mechanism within the main body. Patent Document 2 also discloses an inspection robot that can be operated from outside the rotating electrical machine using a remote device.

[0003] JP 2018-132402 A JP 2002-209363 A

[0004] The flaw detection device disclosed in Patent Document 1 is a probe-integrated ultrasonic flaw detection device, and the ultrasonic probe is connected to a probe drive mechanism and mounted inside the main body, which makes it difficult to change or replace the ultrasonic probe to suit the object to be inspected and the target defect. Furthermore, the pressure of the ultrasonic probe against the object to be inspected is controlled by the probe drive mechanism, which makes it difficult to reproduce the fine adjustments of the pressure made by a skilled inspector. Furthermore, because the ultrasonic vibrations emitted from the ultrasonic probe are transmitted to the object to be inspected via a gel-like elastic member, the ultrasonic probe and the elastic member are bonded together, which makes it difficult to reproduce the scanning technique of a skilled inspector who slides the ultrasonic probe over the surface of the object to be inspected.

[0005] The inspection robot disclosed in Patent Document 2 requires not only an inspection device that functions as a flaw detection mechanism, but also peripheral devices such as a traveling device including a robot support mechanism such as a pantograph jack, a remote control device for transmitting power and control signals to the mechanism, and a transmission cable, resulting in the problem of extensive inspection equipment and preparation work. Furthermore, because the remote control device is generally installed outside the rotating electric machine, an inspector is required to operate the remote control device outside the rotating electric machine, and a worker is required inside the rotating electric machine to insert, remove, and monitor the robot, inevitably increasing the number of workers. Furthermore, because robots have complex mechanisms and are composed of many parts, the inspector's flaw detection sense differs from that of manual ultrasonic flaw detection testing. In addition to the knowledge and skills of ultrasonic flaw detection testing, inspectors are required to have specialized knowledge and skills regarding foreign matter management and robot operation within the rotating electric machine, and mastering these knowledge and skills takes time and money.

[0006] The present application has been made to solve the above-mentioned problems, and aims to provide an ultrasonic flaw detection device for rotating electrical machines that does not require peripheral equipment, has a simple configuration, is capable of finely adjusting the pressure of the ultrasonic probe and scanning by sliding it over the surface of the object to be inspected, and can reproduce the fine adjustment of the pressure made by a skilled inspector.

[0007] The ultrasonic flaw detection device for rotating electric machines disclosed in the present application is characterized by comprising an upper frame connected to one end of a rod-shaped support structure, a lower frame connected to the upper frame by a plurality of elastic mechanisms, a holding mechanism arranged on the back of the surface of the lower frame connected to the elastic mechanism, an ultrasonic probe detachably fixed to the holding mechanism, an ultrasonic flaw detector arranged on the other side of the support structure for controlling the ultrasonic waves of the ultrasonic probe and analyzing the received reflected waves, and a three-dimensional drive mechanism for rotating the ultrasonic probe in accordance with movements other than the movement direction of the support structure according to the shape of the surface of the object to be inspected when the ultrasonic probe is brought into close contact with the surface of the object to be inspected and the support structure is moved linearly.

[0008] The ultrasonic flaw detection device for rotating electrical machines disclosed in the present application does not require any peripheral equipment and has a simple configuration, but by using a three-dimensional drive mechanism to smoothly follow the ultrasonic probe in accordance with the curvature and gradient of the surface of the object being inspected, it is possible to finely adjust the pressure of the ultrasonic probe and to scan by sliding it over the surface of the object being inspected, thereby reproducing the fine adjustment of the pressure made by a skilled inspector.

[0009] Fig. 2 is a diagram for explaining an example of a test being performed with the ultrasonic flaw detection device according to embodiment 1. Fig. 3 is a plan view of the ultrasonic flaw detection device according to embodiment 1. Fig. 4 is a diagram of Fig. 2 as viewed from arrows A and B, where (a) is a diagram as viewed from arrow A and (b) is a diagram as viewed from arrow B. Fig. 5 is a diagram of the ultrasonic flaw detection device according to embodiment 1 when the cover is attached.

[0010] Embodiment 1. A preferred embodiment of an ultrasonic flaw detector for a rotating electrical machine according to the present invention will be described below with reference to the drawings. Note that the same reference numerals are used to designate the same contents and corresponding parts, and detailed description thereof will be omitted.

[0011] 1 is a schematic diagram showing an example of an ultrasonic testing performed on an assembled rotor and stator of a rotating electric machine. When inspecting, for example, the fitting portion of a retaining ring 42 with the rotor 41 without removing the rotor 41 from the stator 31, an inspector 51 enters the rotating electric machine up to near the end of the rotor 41 and inserts an ultrasonic flaw detector 1 into the gap between the rotor 41 and the stator 31. The probe results of an ultrasonic probe 9 attached to the tip of the inserted ultrasonic flaw detector 1 are transmitted to an ultrasonic flaw detector 21, and the inspector 51 can scan the ultrasonic probe 9 while checking the flaw detection results on a display provided on the ultrasonic flaw detector.

[0012] 2 is a side view showing the schematic configuration of the ultrasonic flaw detection device 1. It is composed of a holding mechanism 4 (a collective term for 4a to 4d) for holding an ultrasonic probe 9, a three-dimensional drive mechanism 2 and an elastic mechanism 3 for controlling the orientation and pressing force of the ultrasonic probe 9, and a support mechanism 5 for an inspector 51 to operate the ultrasonic probe 9 held by the holding mechanism 4. Each component will be explained below.

[0013] The support mechanism 5 is rod-shaped, supporting the ultrasonic probe 9 at one end and forming a gripping portion at the other end that allows an inspector 51 to grasp the support mechanism and perform scanning. To allow the ultrasonic probe 9 to be closely attached to the surface of the object under inspection for scanning, the support mechanism 5 does not directly support the ultrasonic probe 9. Instead, the support mechanism 5 secures an upper frame 7 with a connecting portion 6 attached to one end. The upper frame 7 is connected to a lower frame 8 via an elastic mechanism 3 and a three-dimensional drive mechanism 2 (described later). The ultrasonic probe 9 is detachably attached to the lower frame 8 by a holding mechanism 4 disposed on the surface (back surface) opposite to the surface facing the upper frame 7. The support mechanism 5 is also required to be durable during flaw detection. For example, as shown in FIG. 3( a), a convex portion 5a1 may be formed at the end of one unit 5a, and a concave portion 5a2 may be formed at the end of the other unit 5a facing the first unit 5a, forming a rod-type structure that allows the units 5a to be connected and disassembled. With this configuration, the support mechanism 5 can be adjusted to the required length to suit the inspection position. Using screws to connect each unit 5a prevents accidental disassembly during flaw detection and ensures sufficient strength. The support mechanism 5 may also be equipped with a grip made of rubber or other material to make it easier for the inspector 51 to hold and operate. By using a rod-type support mechanism 5 that does not have a complex mechanism, there is no need for skill management, such as special training for the inspector 51.

[0014] The holding mechanism 4 may be, for example, a screw-type holding mechanism consisting of holding plates 4a, 4b, and screws 4c, as shown in FIG. 2 . Specifically, a holding plate 4a with a threaded hole and a holding plate 4b without a threaded hole are arranged on the lower frame 8 so that they face each other, and a screw 4c is screwed into the holding plate 4a. The ultrasonic probe 9 is clamped between the screw 4c and the holding plate 4b. A non-slip surface 4d may be attached to the tip of the screw to prevent the ultrasonic probe 9 from slipping or rotating. The screw-type holding mechanism makes it difficult for the force holding the ultrasonic probe 9 to loosen during ultrasonic testing, preventing the ultrasonic probe 9 from falling off during testing. Because the structure is very simple, the external dimensions of the holding mechanism 4 can be reduced, allowing it to be easily inserted into the narrow space between the rotor 41 and the stator 31. Furthermore, the ultrasonic probe 9 can be held regardless of the shape of the ultrasonic probe 9, which is changed or replaced to suit the target to be tested.

[0015] Note that a clamp-type holding mechanism that clamps the ultrasonic probe 9 using a toggle-type holding mechanism may be used instead of the screw-type holding mechanism. However, in this case, the structure becomes more complex than with a screw-type holding mechanism, and the external dimensions of the holding mechanism 4 become larger. To solve this problem, the height of the holding mechanism 4 may be reduced by clamping from a horizontal direction rather than a vertical direction relative to the flaw detection surface.

[0016] In order to smoothly follow the surface of the object to be inspected (in this embodiment, the outer peripheral surface of the portion where the retaining ring 42 is fitted with the rotor 41), the ultrasonic probe 9 held by the holding mechanism 4 must be able to assume an arbitrary angle that matches the curvature and gradient of the surface of the object to be inspected. This is achieved by configuring the lower frame 8 on which the holding mechanism 4 is mounted to be rotatable relative to the upper frame 7. On the other hand, since the inspector 51 can control linear movement in the forward, backward, left, and right directions by moving his or her hand via the support mechanism 5, horizontal movement in the same direction as the movement of the support mechanism 5 of the ultrasonic flaw detection device 1 itself would actually be a hindrance when performing flaw detection. For these reasons, the three-dimensional drive mechanism 2 may have a swivel structure as shown in FIG. 3(b). Specifically, in Figure 3(b), a rotatably held member 2b and a lower frame 8 are connected within a support structure 2a supported by an upper frame 7, and the lower frame 8 is allowed to rotate so that it can assume any angle relative to the upper frame 7, thereby allowing the ultrasonic probe 9 held by a holding mechanism 4 arranged on the back of the lower frame 8 to rotate freely.

[0017] As shown in FIG. 3 , elastic mechanisms 3 are connected at three locations around the three-dimensional drive mechanism 2 between the upper frame 7 and the lower frame 8 to suppress unintended rotational movement of the three-dimensional drive mechanism 2, control the posture of the ultrasonic probe 9, and maintain a constant and uniform pressure on the ultrasonic probe 9 to facilitate posture control. The three elastic mechanisms 3 suppress rotational movement of the three-dimensional drive mechanism 2 around an axis that perpendicularly penetrates the upper frame 7 and the lower frame 8. Various materials, such as rubber, resin, and various polymeric materials, can be used for the elastic mechanism 3 depending on the required pressure and the target object of inspection. However, a spring is used in FIG. 2 to illustrate the basic configuration. The spring engages with fasteners formed on the upper frame 7 and the lower frame 8. The number of elastic mechanisms 3 connected is not limited to three.

[0018] The three-dimensional drive mechanism 2 and elastic mechanism 3 are required to perform flaw detection in accordance with the curvature and gradient of the surface of the object to be inspected, but if the curvature and gradient of the surface of the object to be inspected is small, it may be possible to adequately follow it using only the elastic force of the elastic mechanism 3. In this case, the three-dimensional drive mechanism 2 may not be provided, and the upper frame 7 and the lower frame 8 may be connected only by the elastic mechanism 3. With this configuration, the outer diameter of the ultrasonic flaw detection device 1 can be reduced, making it possible to insert it into a smaller space.

[0019] The ultrasonic probe 9 has an ultrasonic vibrator inside, and transmits ultrasonic vibrations from the ultrasonic vibrator from the surface to the inside of the object to be inspected, and evaluates flaws present in the object to be inspected based on the time it takes for the reflected wave to return and the strength of the reflected wave. Signal lines for transmitting signals to vibrate the ultrasonic vibrator, signal lines for received reflected wave signals, signal lines for controlling the ultrasonic vibrator, etc. are connected to the outer periphery of the ultrasonic probe 9, and these signal lines are connected to the ultrasonic flaw detector 21 operated by the inspector 51.

[0020] The ultrasonic flaw detector 21 outputs a control signal to control the frequency of the ultrasonic vibrator in the ultrasonic probe 9, and receives a signal of a reflected wave from the ultrasonic probe 9 to analyze the state of flaws in the object to be inspected, and displays the result on a display so that the inspector 51 can visually confirm it. The ultrasonic flaw detector 21 is composed of a processor and a storage device, and the storage device includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory. The processor executes a program input from the storage device to, for example, control the frequency of the ultrasonic probe 9 or analyze the state of flaws in the object to be inspected using the reflected wave. In this case, the program is input from the auxiliary storage device to the processor via the volatile storage device. The processor may also output data such as analysis results to a volatile storage device in the storage device, or may store the data in the auxiliary storage device via the volatile storage device.

[0021] The operation of the ultrasonic flaw detection device 1 configured as described above will now be described. The inspector 51 operates the ultrasonic flaw detection device 1 through the support mechanism 5. The support mechanism 5 must be long enough to reach the flaw detection location. However, because the rotating electrical machine where the work is performed is narrow and space is limited, an excessive length would impair operability. Therefore, the support mechanism 5 detaches or connects the unit 5a to match the distance to the flaw detection location, adjusts the length of the support mechanism 5, and then begins scanning. At the start of scanning, the inspector 51 manually moves the ultrasonic flaw detection device 1 linearly over the surface of the object to be inspected until it reaches the desired flaw detection location. Therefore, the tip of the support mechanism 5 moves within a range visible to the inspector 51. The ultrasonic probe 9 attached to the tip of the ultrasonic flaw detection device 1 is then brought into close contact with the outer peripheral surface of the fitting portion of the retaining ring 42 with the rotor 41, which is the flaw detection range. The inspector 51 then operates the ultrasonic flaw detector 21 attached to the support mechanism 5 at his / her hand. While emitting ultrasonic waves of a set frequency from the ultrasonic probe 9, the inspector 51 moves his / her hand holding the support mechanism 5 linearly back and forth and left and right, thereby moving the support mechanism 5 linearly back and forth and left and right, thereby moving the ultrasonic probe 9 attached to the tip of the support mechanism 5 over the object to be inspected in the same direction as the movement of the support mechanism 5. To prevent the ultrasonic probe 9 from coming loose from the surface of the object to be inspected during scanning, the three-dimensional drive mechanism 2 rotates the ultrasonic probe 9 in accordance with the curvature and gradient of the surface of the object to be inspected, thereby allowing it to follow movement in directions other than the linear direction. The elastic mechanism 3 then moves the ultrasonic probe 9 along the surface of the object to be inspected while maintaining a constant and uniform pressing force of the ultrasonic probe 9. The reflected waves from the ultrasonic probe 9 are converted into electrical signals and transmitted to the ultrasonic flaw detector 21, and the state of the flaw is detected based on the electrical signals of the reflected waves received by the ultrasonic flaw detector 21.

[0022] Fig. 4 is a side view showing a schematic configuration when the cover 10 is attached to the ultrasonic flaw detector 1 of Fig. 2. For the purpose of foreign matter management within the rotating electrical machine, the cover 10 is attached so as to cover the three-dimensional drive mechanism 2 and the elastic mechanism 3, which have a particularly large number of parts and connections. The cover material may be an elastic material such as rubber or resin, or a material with an elastic structure such as a bellows, so as not to impede the functions of the three-dimensional drive mechanism 2 and the elastic mechanism 3.

[0023] With the above-described configuration, the ultrasonic flaw detection device 1 has the following advantages: (1) Because it is configured to be inserted into narrow spaces such as the gap between a rotor and a stator, ultrasonic flaw detection testing can be performed outside a rotating electric machine within a visible range close to the rotating electric machine. (2) The ultrasonic probe can be easily changed or replaced to suit the object to be inspected and the target defect. (3) Despite its simple mechanism, the ultrasonic probe's pressing force can be finely adjusted and it can be scanned by sliding it over the surface of the object to be inspected, reproducing the fine pressing force adjustments made by experienced inspectors. (4) No peripheral equipment is required, reducing the equipment, preparation work, and personnel required for inspection. (5) Because the flaw detection feel is similar to that of manual ultrasonic flaw detection testing and the mechanism is simple, special training in specialized knowledge and skills to operate the inspection device is not required.

[0024] Although exemplary embodiments are described in this application, the various features, aspects, and functions described in the embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, variations in, addition to, or omission of at least one component are included.

[0025] 1: ultrasonic flaw detection device, 2: three-dimensional drive mechanism, 3: elastic mechanism, 4: holding mechanism, 5: support mechanism, 6: connection part, 7: upper frame, 8: lower frame, 9: ultrasonic probe, 10: cover.

Claims

1. an ultrasonic flaw detection device for a rotating electric machine, comprising: an upper frame connected to one end of a rod-shaped support structure; a lower frame connected to the upper frame by a plurality of elastic mechanisms; a holding mechanism arranged on the back of the surface of the lower frame connected to the elastic mechanism; an ultrasonic probe detachably fixed to the holding mechanism; an ultrasonic flaw detector arranged on the other side of the support structure for controlling the ultrasonic waves of the ultrasonic probe and analyzing the received reflected waves; and a three-dimensional drive mechanism for rotating the ultrasonic probe in accordance with movements other than the movement direction of the support structure in accordance with the shape of the surface of the object to be inspected when the ultrasonic probe is brought into close contact with the surface of the object to be inspected and the support structure is moved linearly.

2. The ultrasonic flaw detection device for a rotating electric machine according to claim 1, characterized in that the three-dimensional drive mechanism has a swivel structure consisting of a support fixed to the upper frame and a member having one end rotatably fitted into the support and the other end fixed to the lower frame.

3. The ultrasonic flaw detection device for a rotating electric motor as described in claim 2, characterized in that the three-dimensional drive mechanism is arranged surrounded by the multiple elastic mechanisms, and the multiple elastic mechanisms suppress the rotational movement of the three-dimensional drive mechanism around an axis that vertically passes through the upper frame and the lower frame as the rotation axis.

4. An ultrasonic flaw detection device for a rotating electric motor as described in any one of claims 1 to 3, characterized in that the holding mechanism is configured such that a first holding plate with a screw hole and a second holding plate without a screw hole are arranged on the lower frame facing each other with a gap between them, and the ultrasonic probe is clamped between a screw threaded into the first holding plate and the second holding plate.

5. 4. The ultrasonic flaw detector for a rotating electrical machine according to claim 1, wherein the upper frame, the lower frame, the three-dimensional drive mechanism, and the elastic mechanism are covered with a cover.

6. An ultrasonic flaw detection device for a rotating electric machine as described in any one of claims 1 to 3, characterized in that the support structure is configured so that its length can be adjusted according to the flaw detection position of the test object by separating and connecting multiple unit components.