JP2001066271A - Method and device for inspecting point welding part of pump impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the point welding part inspection method and device of a pump impeller for quickly and accurately inspecting the completeness of a number of point welding parts. SOLUTION: In the inspection method, point welding parts 5 and 6 of a pump impeller 1 that is composed by performing the point welding of thin-plate press forming members 2, 3, and 4 are inspected by capturing heat being generated by Joule heat by energization using an infrared image device. In the inspection method, the inner-periphery and outer-periphery end faces of a wheel base 2 at the side of a surface to be inspected, and the inner-periphery and outer- periphery end faces of a wheel plate 3 at the side of an opposite surface to be inspected, are set to an energization part with the same potential for energization, thus obtaining an infrared image by the infrared image device on the opposite outer surface of a point welding part 5 of the wheel plate 3 at the surface to be inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump impeller for non-destructively evaluating the soundness of each welded point (weld point) of a centrifugal pump impeller formed by spot welding thin press-formed members. The present invention relates to a welding part inspection method and apparatus.

[0002]

2. Description of the Related Art In a small centrifugal pump impeller, for example, a thin plate material such as stainless steel is press-formed for each part such as a main plate, a wing plate, and a side plate, and these parts are spot-welded to constitute a pump impeller. That is being done. In this type of pump impeller, in addition to a large static load due to pressure, torque and centrifugal force, a vibration load also acts on each point weld, so that all point welds are sound welding. It is desired.

In the case of a small pump impeller having a narrow passage width,
Generally, 20 to 100 point welds are simultaneously welded, and one of the surfaces to be welded is generally a shearing cut surface, so that the contact pressure between the members to be welded, that is, the contact resistance differs for each point weld, and The soundness may vary. Conventionally, the inspection of the soundness of this spot weld has been performed by a sampling destruction test, but this is poor in reliability,
All items could not be inspected.

[0004] Various proposals have been made for heating and / or cooling a structure to give a temperature gradient, and detecting the surface temperature distribution with an infrared imager to detect material defects on the surface and inside of the structure. . It has also been proposed to energize as a heating means for providing this temperature gradient. It has also been proposed to increase the inspection sensitivity by coating a high infrared transmission film or a high emissivity film on the surface to be inspected.

[0005]

In a centrifugal pump impeller having a main side plate having a thin spot welding structure, which is an object of the present invention, when an infrared image is used to check the soundness of the weld, there are several problems. There are issues. The target impeller is generally manufactured continuously within one minute of the tact time, and it is desired that all the inspection be performed.
It is necessary that the application of the temperature gradient, the recording of the infrared image data or the judgment of the inspection result, and the removal of the impeller from the inspection device can be performed within one minute. Even if a temperature gradient is applied by internal heating by energization, the infrared radiation distribution on the outer surface of the impeller, which has 20 to 100 welding points with substantially the same temperature gradient and separates the thickness of the impeller board from the welding point It is a practically important issue how to apply power in order to have a correlation with welding integrity.

In addition, many of the target impellers are manufactured from a cold-rolled stainless steel sheet and have a low infrared emissivity and a high infrared reflectivity, so that a slight temperature gradient can be assured without being affected by disturbances such as lighting. There is a strong demand for the development of a simple and inexpensive method for the detection of DNA. In addition, the application of a matte black paint or the like has difficulty in drying time and removal after inspection.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method and an apparatus for inspecting spot welds of a pump impeller, which can inspect the soundness of many spot welds in a short time and with high accuracy. The purpose is to do.

[0008]

According to a first aspect of the present invention, there is provided a method for inspecting a spot weld of a pump impeller, wherein a spot weld of a pump impeller formed by spot welding a thin plate press-formed member is energized. An inspection method for capturing and inspecting heat generated by Joule heat generated by an infrared imaging device, wherein an inner peripheral end surface and an outer peripheral end surface of the inspected side vehicle body, and an inner peripheral end surface and an outer peripheral end surface of the opposite inspected surface side vehicle body are inspected. Energize each as the energizing part of the same potential,
An infrared image is obtained by the infrared imaging device on the outer surface of the vehicle body on the side of the inspection surface opposite to the spot weld. According to the present invention, the current flows from each side of the main plate and the side plate as a parallel circuit in all the point welds, and the current-carrying cross-sectional area of the point weld is calculated from the current-carrying cross-sectional area of the main plate, the side plate and the wing plate. Because it is extremely small, the current density at each point weld is significantly increased, and heat is concentrated at each point weld,
The temperature distribution corresponds to the soundness of each point weld. If the spot weld has a defect, the defective spot weld has a higher resistance and a higher calorific value than a sound spot weld, and does not generate heat when the weld is peeled off. By capturing these states with an infrared imaging device, all spot welds can be inspected at once.

A second aspect of the method for inspecting spot welds of a pump impeller according to the present invention is to heat a spot weld of a pump impeller formed by spot welding thin plate press-formed members due to Joule heat generated by energization. Is inspected by capturing an image with an infrared imaging device, wherein the outer peripheral end surface of the inspected surface side vehicle between the inner peripheral end surface of the inspected surface side vehicle and the outer peripheral end surface of the opposite inspected surface side vehicle. And applying an electric current between the inner peripheral end face of the opposite side of the inspected vehicle and obtaining an infrared image by the infrared imaging device on the outer surface on the opposite side of the spot welded portion of the inspected surface of the vehicle. Is what you do. According to the present invention, for example, when the required amount of current is small, the supply current flows through all the spot welds, and the temperature distribution and the soundness of the spot welds can be made to correspond to each other as in the first embodiment. it can.

[0010] In a preferred aspect of the present invention, two infrared imaging devices are used to simultaneously inspect spot welds on both vehicle sides. This enables efficient inspection.

A third aspect of the method for inspecting spot welds of a pump impeller according to the present invention is that a spot weld of a pump impeller formed by spot welding a thin plate press-formed member is heated by Joule heat generated by energization. Inspection method for capturing and inspecting with an infrared imaging device, at least one of the inner peripheral end surface and the outer peripheral end surface of the inspected surface side car body as a current-carrying portion of the same potential, and the entire surface of the opposite side of the vane plate side It is characterized in that a current is supplied as a counter-current-carrying portion having the same potential, and an infrared image is obtained by the infrared image device on the outer surface on the opposite side of the spot-welded portion of the vehicle body on the inspection surface side. According to the present invention, even when an open impeller without a side plate or at a stage where only one vehicle is welded, a supply current flows through all spot welds,
Inspection of spot welds can be performed.

Here, the power source to be energized is a low voltage alternating current of a commercial frequency, and the current is 20 to 100 A per welding point. This makes it possible to reduce the size and cost of the apparatus, raise the temperature to about 1 to 4 ° C., at which inspection can be easily performed with a general infrared imaging apparatus, and prevent the material from being adversely affected by heat generation.

A fourth aspect of the method for inspecting spot welds of a pump impeller according to the present invention is that a spot corresponding to a welding nugget on the image monitor surface of the infrared imaging apparatus has a nugget area of 4 to 4 times at the time of sound welding. Placing a mask with a 20-fold similar area or circular opening, or converting the image signal outside the similar area range or outside the circular range to an erased image, and setting a predetermined spot welding portion for sound welding It is characterized by judging the soundness of welding by comparing it with an image. According to the present invention, an objective evaluation can be performed in a short time without processing a huge amount of image data.

A fifth aspect of the method for inspecting spot welds of a pump impeller according to the present invention has a planar shape substantially the same as the shape of the surface of a vehicle body to be inspected, and is provided at a position opposed to a welding nugget when sound welding is performed. A mask in which an opening having a similar area or a circular opening of 4 to 20 times the nugget area of the above-mentioned nugget is closed with a translucent or opaque thin film having an adhesive layer on one side, and the center of the nugget-facing position on the surface to be inspected is substantially the thin film. The inspection is performed by adhering to the surface to be inspected so as to be at the center of the inspection. ADVANTAGE OF THE INVENTION According to this invention, disturbance by external light, such as factory lighting, is eliminated, even a slight temperature rise is reliably detected, and the drying wait time when applying paint etc. is not required. Further, the mask can be easily removed after the inspection.

A first aspect of the apparatus for inspecting spot welds of a pump impeller according to the present invention is to provide an infrared image of a spot weld of a pump impeller constructed by spot welding a thin press-formed member. An inspection device that is captured and inspected by the device, and a ring-shaped inspection side surface collet that energizes at least one of an outer peripheral end surface and an inner peripheral end surface of the inspected surface side vehicle board,
It is characterized in that it has a ring-shaped anti-inspection surface side collet that is energized to at least one of the outer peripheral end surface and the inner peripheral end surface of the anti-inspection surface side vehicle body. According to the present invention, the inspected impeller has a thin plate structure, and at least one of the inner and outer peripheral end faces is a current-carrying part even if the inner and outer peripheral ends of the main plate and the inner and outer peripheral ends of the side plates have irregularities due to the shearing cross section. Therefore, the accumulated circumference can be lengthened to increase the contact area, and even if a large contact pressure is applied, the deformation and damage of the impeller can be prevented, and the current can be supplied uniformly from the entire circumference.

A second aspect of the apparatus for inspecting spot welds of a pump impeller according to the present invention is an infrared image of a spot weld of a pump impeller formed by spot welding a thin press-formed member. A ring-shaped inspection surface side collet that is energized to at least one of an outer peripheral end surface and an inner peripheral end surface of the inspected surface side vehicle, which is an inspection device captured and inspected by the device,
A disk-shaped current-carrying terminal for energizing the entire surface of the vane-side end surface opposite to the surface of the vehicle to be inspected is provided. According to the present invention, an open impeller without side plates,
Even at the stage where only one vehicle body is welded, the inspection of the spot welds can be performed by supplying the supply current to all the spot welds.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a principle diagram of an inspection method according to a first embodiment of the present invention. As shown in FIG. 1, a pump impeller 1 having a spot welding structure is configured by joining a main plate 2, a side plate 3, and a wing plate 4 formed by pressing a cold-rolled stainless steel sheet into a predetermined shape by spot welding. ing. In this case, the main plate 2 and the wing plate 4 are
Thus, the side plate 3 and the wing plate 4 are spot-welded at the spot welds 6 respectively. According to the present invention, the welding soundness of each of the spot welds 5, 6 of the pump impeller 1 is inspected.

First, when inspecting the welding soundness of the spot weld portion 5 between the main plate 2 and the wing plate 4, the main plate (vehicle to be inspected) 2
Are connected by conducting wires 9 and 10 as inner conductors 8 having the same potential as the outer conductors 7 and the inner peripheral end surfaces are connected to the outer conductors 7 and 10 by outer conductors. Energizing unit 1
1. The inner peripheral end face is connected by conducting wires 13 and 14 as an inner conducting member 12 having the same potential as the outer conducting member 11, and these conducting wires 9 and 1 are connected.
Current is supplied to AC power supplies 0, 13, and 14 from an AC power supply 15. Then, current flows from all sides of the main plate 2 and the side plate 3 in parallel at the all-point welded portions 5 and 6. That is, the current from the main plate 2 side flows inside the main plate 2, flows through all the spot welds 5 of the main plate 2 and the wing plate 4 in parallel, then flows inside the wing plate 4, and the side plate 3 and the blade After flowing through all the spot welds 6 with the plate 4 in parallel, it reaches the side plate 3. The current from the side plate 3 flows in the opposite direction.

Here, the current-carrying sectional areas of the spot welds 5 and 6 are as follows:
Since the current-carrying cross-sectional area of the main plate 2, the side plate 3, and the blade plate 4 is significantly smaller than the current-carrying cross-sectional area, the current density becomes remarkably high, and the spot welds 5, 6
It generates heat intensively. Here, if a material defect such as “fly”, “scatter” or partial crack is present in any of the spot welds, the cross-sectional area of the spot weld decreases,
Since the resistance is higher than that of a healthy spot weld, the current flowing through the spot weld decreases and heat is generated more. Since the thickness of the main plate 2 and the side plate 3 is generally thin and constant at 1 to 3 mm, a change in the temperature distribution corresponding to the calorific value of the spot welds 5 and 6, that is, the degree of the welding defect, is immediately after the start of energization (heating). It occurs on the surface of the impeller 1. Therefore, by obtaining an infrared image of the outer surface of the main plate 2 with an infrared imaging device installed on the axial extension of the outer surface of the main plate 2, welding defects of all the spot welds 5 between the main plate 2 and the wing plate 4 are eliminated. Can be detected in a short time.

As described above, the current-carrying cross-sectional area of the main plate 2 and the side plate 3 is orders of magnitude larger than that of the welded portion, so that when the inner and outer peripheral end surfaces of the main plate 2 and the inner and outer peripheral end surfaces of the side plate 3 are supplied with current, respectively, If the properties, that is, the soundness, of the spot welds 5, 6 are the same, the current flowing through each spot weld 5, 6 becomes substantially the same, and exhibits a substantially constant heat generation and temperature distribution. Therefore,
In a short time after the start of energization, that is, within a range in which temperature diffusion due to heat conduction in the main plate 2 and the side plate 3 does not progress, the spot welds 5, 6
And the temperature distribution depends only on the welding soundness without being affected by the number and position of the welding. When the spot weld is peeled off, no heat is generated. Therefore, a spot weld having increased heat generation and a spot weld having no heat generation in the infrared image obtained by the infrared imaging apparatus can be determined to be a defective spot weld.

As will be described later, the supply current to the test impeller needs to be 1000 A or more, and it is desired to increase the contact area and contact pressure of the current-carrying terminals. The target impeller has a thin plate structure, and the inner and outer peripheral edges of the main plate and the outer peripheral edge of the side plate have unevenness due to the cutting plane of the shearing surface. Therefore, even if a large contact pressure is applied, the impeller is not deformed or damaged, and the current can be uniformly supplied from all around.

When the required amount of current is small, FIG.
As shown in FIG. 2, the outer peripheral end surface of the main plate (the vehicle surface to be inspected) 2 is connected to the conductor 9 as an outer peripheral conducting portion 7, and the inner peripheral end surface of the side plate (anti-inspection surface side vehicle) 3 is connected to the inner peripheral conducting portion 12. And an electric current is supplied to these conductors 9 and 14 from an AC power supply 15. Further, as shown in FIG. 2B, the inner peripheral end face of the main plate (vehicle to be inspected) 2 is used as an inner peripheral energizing section 8 for conducting wire 10.
The outer peripheral end face of the side plate (anti-inspection surface side vehicle panel) 3 is connected as a peripheral conducting section 11 by a conductor 13, and these conductors 10,
A current is supplied to the AC power supply 13 from an AC power supply 15. Even in the configuration shown in FIGS. 2 (a) and 2 (b), since the supply current passes through all the spot welds 5 and 6, the above-described method in which the inner and outer peripheral ends of each of the main side plates are energized. Similarly, the temperature distribution and the welding soundness of the spot welds correspond.

In the above, the main plate 2 is used as the vehicle to be inspected and the spot weld 5 between the main plate 2 and the wing plate 4 is used as the main plate 2.
Inspection is carried out by an infrared imaging device installed on the axial extension of the outer surface of the side plate. Another infrared imaging device is installed on the axial extension of the outer surface of the side plate 3, and this infrared imaging device is used. The spot welds 6 between the side plate 3 and the wing plate 4 may be inspected simultaneously. As a result, the inspection of the welded portions of both vehicle panels can be performed simultaneously, and an efficient inspection is possible.

FIG. 3 shows the principle of the inspection method according to the second embodiment of the present invention applied to an intermediate inspection at a stage where the main plate 2 and the wing plate 4 are spot-welded at the spot welding portion 5. . In the example shown in FIG. 3, the outer peripheral end face of the main plate (inspection side car body) 2 is defined as an outer conductive section 7, and the inner peripheral end face is defined as an inner conductive section 8 having the same potential as the outer conductive section 7. And a disc-shaped current-carrying terminal (opposite current-carrying part) 1 on the free end side end face 18 of the wing plate 4.
6 are brought into contact with each other, and the current-carrying terminals 16 are connected by conducting wires 17 so that an electric current is supplied to these conducting wires 9, 10 and 17 from an AC power supply 15. In this example, the main plate 2
The current from the side flows inside the main plate 2 and the main plate 2 and the wing plate 4
After flowing through all the spot welds 5 in parallel with each other, it flows through the inside of the blade plate 4 and reaches the energizing terminal 16. The current from the power supply terminal 16 flows in the opposite direction. In other words, the same inspection as that of the closed impeller is made possible by using the energizing terminals 16 to make the end surfaces of the red welding side of all the blades the opposite energizing portions of the same potential. Thus, as described above, by obtaining an infrared image of the outer surface of the main plate 2 with an infrared imaging device placed on the axial extension of the outer surface of the main plate 2, all spot welding of the main plate 2 and the wing plate 4 is performed. The welding soundness of the portion 5 can be detected in a short time.

Although this example shows an example in which the present invention is applied to an intermediate inspection at a stage where the main plate and the wing plate are spot-welded, an intermediate inspection at the stage where the side plate and the wing plate are spot-welded, It can also be applied to the inspection of open impellers without any.

In the example shown in FIGS. 1 to 3, the supply current is suitably 20 to 100 A per one welding point on one side of the surface to be inspected. Generally, the resistance between both ends of a welding point nugget of a centrifugal pump impeller having a spot welding structure is about several milliohms. Therefore, when a current of 20 to 100 A is applied per welding point, the input power is about 5 to 20 W per welding point, and The temperature rises to about 1 to 4 ° C within 2 to 2 seconds after the start of energization at the position facing the welding nugget on the inspection surface, making it easy to inspect in a short time with a general infrared imager, and adversely affecting the material due to heat generation Nor.

The welding point of the target impeller is designed to be 20 to 70 points on one side of the vehicle body.
Although 100 to several thousand A is required, the voltage is as low as about 0.5 V and the electric power is as small as 0.1 to several Wh. Further, if the power supply for energization is a low-voltage AC of commercial frequency, the device is simple and inexpensive, and the installation space can be small.

Next, an inspection apparatus using the principle shown in FIG. 1 will be described with reference to FIGS. FIG. 4 is a longitudinal sectional view showing an impeller to be inspected and an inspection device, and FIG. 5 is a transverse sectional view thereof. As shown in FIGS. 4 and 5, the inspection device includes a ring-shaped main plate outer peripheral collet 20 that energizes the outer peripheral end surface of the main plate 2, a ring-shaped main plate inner peripheral collet 21 that energizes the inner peripheral end surface of the main plate 2, A ring-shaped side plate outer peripheral collet 22 that energizes the outer peripheral end surface of the side plate 3 and a ring-shaped side plate inner peripheral collet 23 that energizes the inner peripheral end surface of the side plate 3 are provided.

The outer circumferential surface and the inner circumferential surface of the outer peripheral collet 20 of the main plate have slits 2 extending radially alternately.
4, 25 are provided. In addition, side plate outer peripheral collet 22
Similarly, a slit (not shown) is provided. The main plate outer peripheral collet 20 and the side plate outer peripheral collet 22 are arranged on both upper and lower sides with a disk-shaped insulating material 26 interposed therebetween. By tightening the tightening band 28 via the tightening nut 27, the inner circumferential surface of the main plate outer circumferential collet 20 is in close contact with the outer circumferential surface of the main plate 2, and the inner circumferential surface of the side plate outer circumferential collet 22 is in close contact with the outer circumferential surface of the side plate 3. .

On the other hand, the inner peripheral collet 21 of the main plate is closely adhered to the inner peripheral surface of the main plate 2 by the main plate tapering 30, the bolt 31 and the nut 32, and the inner peripheral collet 23 of the side plate is attached to the inner peripheral surface of the side plate 3. The taper ring 33, the sleeve 34 and the nut 35 make close contact. The main plate inner peripheral collet 21 is also provided with a slit 29, and the side plate inner peripheral collet 23 is also provided with a slit (not shown).
Is provided. The sleeve 34 and the nut 35 are insulated from the bolt 31 and the nut 32 by insulating materials 36 and 37. As a result, the main plate inner peripheral collet 21 and the side plate inner peripheral collet 23 are insulated from each other.

Since the inner and outer peripheral end faces of the main plate 2 and the outer peripheral end face of the side plate 3 are generally uneven at the shearing cut surface and have a small target thickness, a large current for obtaining a calorific value that can be inspected is applied to the vehicle body. The terminals that conduct electricity to the inner and outer peripheral end surfaces of the above are preferably of a collet structure. As shown in FIGS. 4 and 5, a collet having a radial slit is deformed so as to increase or decrease the inner or outer diameter of the collet by tapering or banding, and the inner and outer peripheral end faces of the impeller vehicle board. And firm contact. As a result, it is possible to set the subject in a short time, to secure a uniform power supply amount, and to increase the power supply amount per unit contact area.

The main plate outer peripheral collet 20 and the bolt 31
Are connected to the conductors 9 and 10 and are connected to one output terminal of the large current transformer 40 so that they have the same potential.
The side plate outer peripheral collet 22 and the side plate inner peripheral collet 23 are connected to the conducting wires 13 and 14 and are connected to the other output terminal of the large current transformer 40 so that they have the same potential. Power is supplied from the commercial AC power supply 15 to the input terminal of the large current transformer 40 via the switch 41 and the variable transformer 42.

In the above-described configuration, when inspecting the spot welds 5 between the main plate 2 and the wing plate 4 on the main plate 2 side, as shown in FIG. The image device 43 is installed so as to be positioned, the switch 41 is turned on, and a current flows from each side of the main plate 2 and the side plate 3 so that all the spot welds 5 and 6 form a parallel circuit. Thus, an infrared image of the outer surface of the main plate 2 is obtained. Thereby, the welding soundness of all the spot welds 5 between the main plate 2 and the wing plate 4 can be inspected in a short time.

FIG. 6 shows an example of an inspection result of a spot weld between a main plate and a blade plate on the main plate side of a sound pump impeller. FIG. 6 shows a test impeller having an outer diameter of 178 mm, a welding number of 28 on the main plate side, an energizing voltage of 0.34 V,
It is an infrared image at 4 seconds after the start of energization as an energization current of 1850A. All the welding points generate heat relatively uniformly,
All of the spot welds on the main plate side were judged to be practically sound, and agreed with the judgment in the destructive test performed after this test.

FIGS. 7 and 8 show another example of the inspection method according to the present invention, in which a mask is used for increasing the inspection sensitivity and efficiency by adhering to the surface to be inspected of a vehicle body. . In this example, a similar opening or circular opening 51 having a cross-sectional area of 4 to 20 times the cross-sectional area of the nugget 50 at the time of sound welding is used.
a, and a translucent or opaque mask 51 having an adhesive layer 52 on one side and previously closed with a thin film 53 having high thermal conductivity and infrared emissivity is prepared in advance, and the position of the mask 51 facing the nugget 50 on the surface to be inspected. The inspection is performed with the mask 51 adhered to the surface to be inspected such that the center of the thin film 53 is substantially at the center of the thin film 53. This method is effective for an object having a low emissivity and a high reflectance, such as a cold-rolled stainless steel plate. As a result, even a slight temperature rise can be reliably detected, disturbance due to external light such as factory lighting can be eliminated, and a drying wait time when applying paint or the like is not required. Further, the mask can be easily removed after the inspection.

Examples of the base material of the thin film 53 include acetate, vinyl chloride, cellophane, and papers, and examples of the adhesive include acrylic, rubber, gelatin, and polyvinyl-based materials. Is mentioned. Also,
In order to obtain a high emissivity, it is convenient to mix graphite fine powder or a black pigment in the thin film or to apply a black paint on the anti-adhesive layer side.

Since the side plate generally has a taper, the mask 51 adhered to the side plate is easily deformed along the tapered shape of the side plate 3 as shown in FIG.
For example, it is preferable to provide the same number (for example, seven) of intermittent radial slits 54 as the number of blades.

Here, commercially available copy paper is cut so that the inner and outer diameters are the same as the outer diameter of the mouth ring and the outer diameter of the side plate, and 28 circular openings 51a having a diameter of 14 mm are provided at positions corresponding to the welding points. To form the mask 51. And
A matte black paint is applied to the surface (anti-adhesion layer side) of a commercially available translucent pressure-sensitive adhesive tape (base material: acetate film, pressure-sensitive adhesive: acrylic resin) on the opening 51a of the mask 51,
The thin film 53 cut to a diameter of 22 mm was bonded. In this case, the adhesive layer side of the tape was adhered to a side plate and subjected to inspection.
As a result, there was no reflection of illumination, a temperature resolution of 1 ° C. or less was obtained, and a remarkable effect was recognized.

If the paraffin paper is placed on the adhesive layer side of the previously prepared mask and stored, and the paraffin paper is removed immediately before use and adhered to the test impeller, it is effective to maintain the adhesive activity of the thin film 53.

In addition, a mask having a similar area or a circular opening of 4 to 20 times the nugget area at the time of sound welding is placed at a position corresponding to the contact nugget on the image monitor surface of the infrared imaging apparatus, or the similar area is provided. The image signal outside the range or outside the circular range may be converted into an erased image, and these may be compared with a predetermined sound image at the time of welding to determine the soundness of welding. Thus, an objective evaluation can be performed in a short time without processing a huge amount of image data. The material of the mask may be opaque.

[0041]

As described above, according to the present invention,
Heat is applied to the centrifugal pump impeller with a thin spot welding structure to check the welding soundness from the infrared image of the outer surface of the impeller board. Tens of welding points can be inspected simultaneously and non-destructively in a short time, for example, within one minute, with high reliability. . Further, the power required for the inspection is negligibly small, and the apparatus can be simplified. Therefore, non-destructive inspection of all mass-produced impellers becomes possible.

[Brief description of the drawings]

FIG. 1 is a principle diagram of an inspection method according to a first embodiment of the present invention.

FIG. 2 is a principle diagram showing a modification of FIG.

FIG. 3 is a principle diagram of an inspection method according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional front view showing the inspection apparatus according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view of FIG.

FIG. 6 is a diagram showing an infrared image of a healthy impeller main plate side inspection result.

FIG. 7 is a cross-sectional view showing a state where a mask is attached to a surface to be inspected.

FIG. 8 is a plan view showing the mask of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump impeller 2 Main plate 3 Side plate 4 Blade plate 5, 6-point welded part 7 Outer conduction part 8 Inner conduction part 9, 10, 13, 14, 17 Conductor 11 Outer conduction part 12 Inner conduction part 15 AC power supply 16 Terminal 18 Free end side end face 20 Main plate outer peripheral collet 21 Main plate inner peripheral collet 22 Side plate outer peripheral collet 23 Side plate inner peripheral collet 24, 25, 29 Slit 26 Insulating material 27 Tightening nut 28 Tightening band 30 Main plate tapering 31 Bolt 32, 35 Nut 33 Side plate tapering 34 Sleeve 36, 37 Insulating material 40 Large current transformer 41 Switch 42 Variable transformer 43 Infrared imaging device 50 Nugget 51 Mask 51a Opening 52 Adhesive layer 53 Thin film 54 Radial slit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koichi Kunimasa 11-1, Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Akihiro Osaki 11-1, Haneda Asahi-cho, Ota-ku, Tokyo EBARA F-term (reference) 2G040 AA05 AB08 BA08 BA27 CA02 CA12 CA23 DA06 DA14 DA15 EA02 EA11 EB02 EC03 FA04 HA02 HA11

Claims (5)

[Claims] 1. An inspection method for inspecting a spot weld of a pump impeller, which is formed by spot welding thin press-formed members, by using an infrared imaging device to capture heat generated by Joule heat generated by energization. The inner peripheral end surface and the outer peripheral end surface of the surface side vehicle, and the inner peripheral end surface and the outer peripheral end surface of the anti-inspection surface side vehicle are energized as the same potential conducting portions, respectively, and are opposite to the spot welded portions of the inspected surface side vehicle. A method for inspecting spot welds of a pump impeller, wherein an infrared image is obtained by the infrared imaging device on a side outer surface. 2. A method for inspecting a spot welded portion of a pump impeller formed by spot welding thin plate press-formed members by detecting heat generated by Joule heat generated by energization with an infrared imaging device. At least one of the inner peripheral end face and the outer peripheral end face of the surface-side vehicle body is a current-carrying portion having the same electric potential, and the entire surface on the opposite side of the vane is energized as a counter-current-carrying portion having the same electric potential. A method for inspecting a spot weld of a pump impeller, wherein an infrared image is obtained by the infrared imaging device on the outer surface on the opposite side of the spot weld. 3. An opening having substantially the same planar shape as the surface of the vehicle body to be inspected and having a similar area or a circular opening of 4 to 20 times the nugget area at the time of sound welding at a position facing the welding nugget. A part of which is covered with a translucent or opaque thin film having an adhesive layer on one side is bonded to the surface to be inspected such that the center of the nugget facing position on the surface to be inspected is substantially the center of the thin film. The method for inspecting spot welds of a pump impeller according to claim 1 or 2, wherein: 4. An inspection apparatus for inspecting a spot-welded portion of a pump impeller formed by spot-welding a thin plate press-formed member by capturing heat generated by Joule heat with an infrared imaging device, comprising: A ring-shaped inspection side surface collet that energizes at least one of the outer peripheral end surface and the inner peripheral end surface of the panel, and a ring-shaped anti-inspection surface that energizes at least one of the outer peripheral end surface and the inner peripheral end surface of the anti-inspection side vehicle body. A spot welding part inspection apparatus for a pump impeller, comprising: a side collet; 5. An inspection apparatus for inspecting a spot welded portion of a pump impeller formed by spot welding thin plate press-formed members by capturing heat generated by Joule heat with an infrared imaging device, comprising: A ring-shaped inspected surface side collet that energizes at least one of the outer peripheral end surface and the inner peripheral end surface of the panel, and a disk-shaped energizing terminal that energizes the entire wing plate side end surface opposite to the inspected surface side vehicle. Inspection apparatus for spot welds of a pump impeller, characterized by having: