JPH0815194A - Method and apparatus for flaw detection of conductive material to be inspected by induction heating - Google Patents

Abstract

PURPOSE:To provide a method and an apparatus for flaw detecting by induction heating in which high flaw detecting accuracy is obtained even when a heating temperature is limited due to the use of emissivity averaging powder even in the case of a nonmagnetic material to be inspected. CONSTITUTION:The surface temperature of a conductive material 10 to be inspected is measured via a slit 76 so formed as to pass the lateral intermediate part of an induction coil 18 in a thickness direction. That is, the surface temperature of the place induction heated by the electromagnetic induction of the coil 18 of the surface of the material 10 to be inspected is measured. Thus, since a flaw decision is conducted based on the temperature detection signal detected within a period in which the temperature distribution due to the flaw is remarkably maintained, even in the case of the nonmagnetic metal in which the temperature distribution is scarcely present due to the flaw with large depth of penetration, the flaw detecting accuracy can be sufficiently obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating flaw detection method and apparatus for flaw detection on a surface flaw based on the non-uniformity of the surface temperature when the surface of a conductive material to be inspected is induction heated.

[0002]

2. Description of the Related Art The surface of a conductive test material is heated by generating an induction current in the conductive test material by electromagnetic induction, and the surface temperature of the conductive test material is measured. An induction heating flaw detection method or device for a conductive inspection material is known, which detects surface flaws on the conductive inspection material based on uniformity. With such a flaw detection method,
When the eddy current generated by electromagnetic induction is concentrated on the skin due to the skin effect, the surface of the conductive material to be inspected is heated by eddy current loss, etc., but the part where the surface flaw exists is more eddy current than other parts. Since the flow rate of No. 2 is changed and the amount of heat generated at that portion also changes, the portion where the surface temperature has changed locally compared to the other portions is determined as a surface flaw.

[0003]

However, in the above-mentioned conventional induction heating flaw detection method, it is general to arrange a radiation thermometer so as to measure the surface temperature of the conductive material to be inspected which has passed through the heating coil. However, in such a case, since the surface temperature is measured in the process in which the temperature distribution due to the flaw generated by the surface heating is averaged by the heat conduction, the flaw detection accuracy cannot be obtained.

In particular, stainless steel, aluminum alloys,
In a conductive inspected material with a large eddy current penetration depth δ and high thermal conductivity, such as a copper alloy, the temperature distribution due to a flaw generated by surface heating is difficult to appear, and even if it appears, the temperature due to the flaw Such inconvenience becomes remarkable because the distribution is easily averaged. Further, when the surface condition of the conductive inspection material is not uniform, for example, when a scratch mark exists, the emissivity of the portion decreases, so that particles such as carbon or titanium are finely coated with an acrylic resin or an epoxy resin for insulation. Induction heating is performed after applying the emissivity-equalized powder, but in order to avoid melting of the insulating coating resin contained in the emissivity-equalized powder, induction heating is performed only up to about 80 to 100 ° C. Therefore, even when using such an emissivity-equalized powder,
The above-mentioned inconvenience becomes noticeable because induction heating can be performed only at a relatively low surface temperature.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to heat a non-magnetic material to be inspected or to use an emissivity uniformized powder. An object of the present invention is to provide an induction heating flaw detection method and apparatus that can obtain high flaw detection accuracy even when the temperature is limited.

[0006]

The first object of the present invention to achieve the above-mentioned object is to generate an induced current in a material to be inspected by electromagnetic induction, so that the material to be inspected is tested. The surface of the conductive test material is heated, the surface temperature of the conductive test material is measured, and based on the non-uniformity of the surface temperature, the surface flaw of the conductive test material is detected. The method comprises the steps of: (a) driving an induction coil placed close to the side surface of a longitudinally-shaped conductive material to be relatively moved in the longitudinal direction at a predetermined speed by driving it with a high-frequency current. A heating step of heating the surface of the inspection material, (b) the temperature of the surface of the conductive inspection material, which is measured by a radiation thermometer at the surface temperature of the location where induction heating is performed by electromagnetic induction of the induction coil. The measurement process
To include.

[0007]

According to this structure, in the heating step, the induction coil arranged in proximity to the side surface of the elongated conductive material to be inspected, which is relatively moved in the longitudinal direction at a predetermined speed, is driven by the high frequency current. As a result, the surface of the conductive inspection material is heated. Further, in the temperature measuring step, the surface temperature of the surface of the conductive inspection material, which is induction-heated by the electromagnetic induction of the induction coil, is measured by the radiation thermometer.

[0008]

As described above, the radiation thermometer measures the surface temperature of the surface of the conductive material to be inspected and where it is induction-heated by the electromagnetic induction of the induction coil, for example, the position immediately below the induction coil. Since the measurement is performed, the defect determination is performed based on the temperature signal ST detected within the period in which the temperature distribution due to the defect is remarkably maintained. Even if the heating temperature is limited because the homogenized powder is used, sufficient flaw detection accuracy can be obtained.

[0009]

The second aspect of the present invention is to provide an apparatus for carrying out the above-mentioned method according to the present invention, in which an induced current is generated in a conductive material to be inspected by electromagnetic induction, and the induced current causes Conductive inspection that heats the surface of the conductive inspection material, measures the surface temperature of the conductive inspection material, and detects flaws on the surface of the conductive inspection material based on the nonuniformity of the surface temperature. An induction heating flaw detector for material, comprising: (a)
An induction coil arranged in proximity to a side surface of a longitudinal conductive material to be inspected, which is moved in the longitudinal direction at a predetermined speed;
(b) a coil driving device that heats the surface of the conductive inspection material by driving the induction coil with a high-frequency current, and (c) a width of the induction coil parallel to the moving direction of the conductive inspection material. A slit formed so as to penetrate in the thickness direction at an intermediate portion of the direction, and (d) a radiation temperature measuring device for measuring the surface surface temperature of the conductive inspection material through the slit in a non-contact manner, It is in.

[0010]

With this configuration, when the coil driving device heats the surface of the conductive inspection target material by driving the induction coil with a high frequency current, the radiation temperature measuring device causes the induction temperature measuring device to detect the conductive inspection target of the induction coil. The surface temperature of the conductive material to be inspected can be measured in a non-contact manner through a slit formed so as to penetrate in the thickness direction at an intermediate portion in the width direction parallel to the moving direction of the material.

[0011]

According to the second aspect of the present invention, the surface temperature of the surface of the elongated conductive material to be inspected, which is induction-heated by the electromagnetic induction of the induction coil, that is, the location corresponding to the intermediate portion in the width direction of the induction coil, Since the temperature is measured by the radiation temperature measuring device, the flaw determination is performed based on the temperature signal ST detected within the period in which the temperature distribution due to the flaw is remarkably maintained. However, even if the heating temperature is limited due to the use of the emissivity-equalized powder, high flaw detection accuracy can be obtained.

Here, it is preferable that the longitudinal conductive test material is a rectangular material having a rectangular cross section, and the slit of the induction coil is one of the four side surfaces of the longitudinal conductive test material. The radiation temperature measuring device is formed to be longer than the width dimension of one side surface, and the radiation temperature measuring device measures the temperature of one side surface of the conductive inspection material through the slit in the entire width direction. With this arrangement, one radiation temperature measuring device can measure the temperature of one side surface of the conductive material to be inspected over the entire width direction, and by providing the radiation temperature measuring device corresponding to the corner portion, the conductivity can be reduced. There is an advantage that surface flaws of the material to be inspected can be detected without leakage.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing an induction heating flaw detector according to an embodiment of the present invention. In the figure, the conductive test material 10 is a rolled billet having a rectangular cross section with a side of about ten and several centimeters and a length of about 10 meters, and is a magnetic metal material such as steel or stainless steel. , A non-magnetic metal material such as an aluminum alloy or a copper alloy.

The conductive material 10 to be inspected is supported by a conveying roller (not shown) and two pinch roller units 12 and 14, and the pinch roller units 12 and 14 are rotatably driven by a driving device (not shown). It is conveyed at a constant speed in the longitudinal direction with the diagonals of the cross section being substantially vertical and horizontal, and in the course of the conveyance, it can be successively passed through the powder coating device 16, the induction coil 18, and the powder removing device 20. ing.

FIG. 2 is a perspective view of the powder coating device 16 as seen from its outlet side. The powder coating device 16 is provided with a through hole 22 which is slightly larger than its cross section for allowing the conductive material 10 to be inspected to pass through.
4, an induction coil 18 having a through hole 26 having a shape slightly larger than its cross section for allowing the conductive material 10 to be inspected, which has come out from the through hole 22, to pass therethrough. The pinch roller unit 14 is composed of a drive roller 28 that is rotationally driven by a drive device (not shown), and a pressing roller 30 that faces the drive roller 28 and presses the conductive inspection target material 10. The pinch roller unit 12 has the same structure as the pinch roller unit 14. Further, the powder removing device 20 is also provided with a through hole 32 like the powder applying device 16.

The powder coating device 16 is, for example, as shown in FIG. 3, a box-shaped main body 17 and powders directed toward the four side surfaces of the conductive inspection material 10 at a predetermined distance in the main body 17. 4 spray guns 3 for ejecting each body 34
6 is provided. The coating gun 36 is located at a fixed distance directly above the widthwise center of each side surface of the conductive inspection material 10. Also, this coating gun 36
4, is a powder supply port 38 connected to a hopper (not shown), a compressed air connection port 40 to which compressed air is supplied, and a discharge port 42 for discharging the powder 34.
And a high-voltage power supply 4 that outputs a negative high voltage of about 100 kV
4 and an electrostatic electrode 46 which is electrically connected to the discharge port 42 and is provided to the discharge port 42, and is configured to inject the negatively charged powder 34. The conductive inspection material 10 is
Conveying roller (not shown) and two pinch roller units 1
Since it is grounded via 2 and 14, powder 3
4 is attracted by the Coulomb force, and is uniformly attracted and applied to the surface of the conductive inspection material 10 according to the principle of electrostatic coating. The powder 34 remaining in the powder coating device 16 is collected via the duct 48.

Further, the powder removing apparatus 20 is, for example, as shown in FIG. 5, a box-shaped main body 21 and four side surfaces of the conductive inspection material 10 which are separated by a predetermined distance in the main body 21. It is provided with four air injection guns 50 which each discharge compressed air of about 4 kg / cm ² . The air injection gun 50 is provided with a plurality of nozzles 52 arranged in the width direction of the side surface of the conductive inspection material 10 so as to project toward the side surface thereof. The powder 34 electrostatically applied to the surface of the conductive material 10 to be inspected is easily removed. The removed powder 34 is collected via the duct 54.

The duct 48 of the powder coating device 16 and the duct 54 of the powder removing device 20 are, as shown in FIG.
It is connected to the dust collector 56 so that the powder 34 remaining in the powder coating device 16 and the powder 34 removed in the powder removing device 20 can be collected in the dust collector 56 and reused. It has become.

That is, the dust collector 56 includes a cyclone type primary dust collector 58 connected to the ducts 48 and 54, and a filter type secondary dust collector 62 connected to the primary dust collector 58 via a duct 60. Through the primary dust collector 58 and the secondary dust collector 62, the powder coating apparatus 1
6 and a suction blower 6 for sucking air in the powder removing device 20
And 4. The primary dust collector 58 is of a type that removes the powder 34 continuously and efficiently in accordance with a centrifugal force by rotating the intake air in an inversely tapered space. The secondary dust collector 62 is of a type that removes the powder 34 having a relatively fine particle size mixed in the air by sucking the intake air through the filter cloth.
The powder 34 collected by the primary dust collector 58 and the secondary dust collector 62 is periodically taken out, cleaned, and then reused.

Here, the powder 34 is carbon particles,
This is emissivity equalizing powder in which particles having a particle diameter of about 40 to 100 μm such as titanium particles are coated with an insulating resin such as epoxy resin or acrylic resin. The carbon particles coated with a resin are black, and the titanium particles coated with a resin are white or gray. All of them emit energy corresponding to the surface temperature, so that The variation in infrared emissivity due to the surface condition is prevented and uniformized, and the emissivity is increased. The insulating resin is for electrically insulating carbon particles, titanium particles, etc., but since it softens or starts melting at a relatively low temperature, the surface heating temperature of the conductive inspection material 10 is at maximum. It is limited to about 100 ° C or less.

In the powder coating device 16, the conductive test material 10 having a rectangular cross section of 150 mm on each side is 40 m long.
While transporting at a speed of about / min, about 90 g / min of the powder 34 is applied to the surface of the conductive inspection material 10,
The discharge amount of the powder 34 from each coating gun 36 is set. At this time, the average coating thickness of the powder 34 on the surface of the conductive inspection material 10 is 7 μm, which is 1/6 of the average particle diameter of the powder 34. That is, the powder 34 is set so as to be sparsely attached on the surface of the conductive inspection material 10.

When the coating thickness of the powder 34 becomes too large and piles up on each other, the conductive material 10 to be inspected
The heat conduction from the surface to the outermost powder 34 is lowered, and infrared radiation of energy corresponding to the temperature of the conductive inspection material 10 cannot be performed. If the coating thickness of the powder 34 becomes too small, the coating effect of the powder 34, that is, the surface of the conductive inspection material 10 is glossy like rubbing traces against each other, and is caused by a portion having a low emissivity. Therefore, it becomes impossible to obtain the effect of increasing the emissivity at a place where the temperature is low and making the emissivity uniform by increasing the emissivity and increasing the emissivity of the whole.
From this point of view, it is desirable that the coating amount of the powder 34 be 1/15 to 1/3 of the average particle diameter.

As shown in FIGS. 6 and 7, the induction coil 18 has a through hole 26 of 20 to 40 mm so as to form a through hole 26 which is slightly larger than the sectional shape of the conductive inspection material 10.
An annular portion 70 in which a strip-shaped metal member of copper or the like having a width dimension is bent in an annular shape, and a straight portion in which both end portions of the strip-shaped metal member are fixed to each other via an insulating plate 72 made of ceramic or resin. And 74. The slit 7 having a width dimension of, for example, about 5 to 10 mm is formed in the central portion in the width direction parallel to the longitudinal direction of the induction coil 18 of the strip-shaped metal member.
6 penetrates in the thickness direction and is formed with a length corresponding to the entire circumference of the annular portion 70. Therefore, as shown in FIG. 8, the temperature of the pair of side surfaces of the conductive inspection material 10 is measured through the slit 76 by the two radiation temperature measuring devices 78a and 78b supported by the frame (not shown). Similarly, the slit 76 is formed by two radiation temperature measuring devices 78c and 78d supported by a frame (not shown).
Through this, the surface temperatures of the two corners of the conductive inspection material 10 are measured.

The radiation temperature measuring devices 78a, 78b, 7
Reference numerals 8c and 78d respectively collect infrared rays radiated from the surface of the conductive test material 10 on the detection surface of an infrared detection sensor in which a large number of detection elements are arranged in the detection surface in a one-dimensional direction (not shown) so as to be conductive. The surface temperature of the measurement point is measured by scanning at a frequency of about 200 Hz in the direction perpendicular to the longitudinal direction of the inspected material 10. 9A shows the temperature detection signal ST corresponding to the temperature distribution in the width direction of the side surface of the conductive inspection object 10 detected through the slit 76 by the radiation temperature measuring devices 78a and 78b. In addition,
As shown in FIG. 6, the induction coil 18 has a hollow structure internally having a cooling liquid passage 80 communicating with the longitudinal direction thereof, and cools heat generated by a high frequency drive current. .

For the purpose of detecting flaws on the surface of the conductive material 10 to be inspected, 100 k
A high frequency drive current having a frequency of about Hz is applied to the induction coil 1 described above.
8 is supplied. As a result, if the conductive material 10 to be inspected is a magnetic metal material, eddy current loss may cause the
It is heated to about 0 μm, and if it is a non-magnetic metal material, it is heated to about 1.5 mm from the surface due to eddy current loss. That is, assuming that the eddy current on the surface of the conductive test material 10 is I ₀ , the frequency is f, the magnetic permeability is μ, and the conductivity is σ, the eddy current I generated in the conductive test material 10 is represented by Formula 1 Decays with respect to the distance x from the surface, as shown in
Let δm be the value of x (permeation depth) where the exponent part of Equation 1 is -1.
If m, then it is expressed by Equation 2. Thus, the eddy current I is concentrated on the surface layer due to the skin effect, so that the surface of the conductive inspection material 10 is heated.

[0026]

[Equation 1]

[0027]

[Equation 2]

The flaw detection control device 66 of FIG.
A well-known microcomputer having M, RAM, etc. is provided, and the temperature detection output from the radiation temperature measuring devices 78a, 78b, 78c, 78d by processing an input signal according to a program previously stored in ROM. Based on the signal ST, surface flaws of the conductive inspection material 10, for example, linear flaws extending in the longitudinal direction of the billet, heddle flaws that are small curved cracks, corner cracks at corners, etc. are determined, and the flaw position is determined. In addition to outputting, a flaw marker (not shown) that displays the flaw position on the surface of the conductive inspection material 10 with ink is operated.

FIG. 10 is a flow chart for explaining a main part of the operation control operation of the flaw detection control device 66, that is, the flaw detection operation while the conductive inspection material 10 is running.

First, by performing a start-up operation (not shown), the conductive material to be inspected 10 is conveyed at a constant speed in the direction of the arrow in FIG. 1, and at the same time, the powder coating device 16 is operated to operate the powder. 34 is attracted to the side surface of the conductive inspection material 10.
After being applied, a high-frequency current is supplied to the induction coil 18, and the powder is removed by the powder removing device 20. At this time,
The induction coil 18 heats the surface of the conductive test material 10 by about 20 to 50 ° C. above room temperature.

In this state, step SS in FIG.
1, the radiation temperature measuring devices 78a, 78b, 78c, 7
1 which is one unit of the temperature detection signal ST output from 8d
It is determined whether or not signals for scanning have been input. Of FIG.
(a) The step is 1 on a predetermined side surface of the conductive inspection material 10.
The temperature detection signal ST for scanning is illustrated. If the determination in step SS1 is negative, the signal for one scan is made to wait until it is input, but if the determination is affirmative, the averaging process of step SS2 and below is executed. In the radiation temperature measuring devices 78a, 78b, 78c, 78d, the processings of step SS2 and thereafter are executed in synchronization with the scanning cycle of the temperature measurement points electrically determined.
The step SS1 corresponds to the temperature detection signal reading step or the temperature detection signal reading means.

In step SS2, the moving average calculation process in which the average value of the input temperature detection signal ST is well known within an appropriate section or the low-pass active filter calculation process having an appropriate cutoff frequency is executed. As a result, the average temperature signal ST _AV is converted. This average temperature signal ST _AV is treated as the surface temperature of a place where no flaw exists, and FIG. 9B illustrates the average temperature signal ST _AV . This step SS2 corresponds to an average processing step or an average processing means.

At the following step SS3, the temperature detection signal is sent.
No. ST to the above average temperature signal ST_AVSubtraction subtraction
Is executed, the surface of the conductive inspection material 10 is
A temperature change amount signal indicating the local temperature change amount in
Defect signal SΔT (ST-ST _AV) Is calculated. Of FIG.
(c) illustrates this flaw signal SΔT. This step
SS3 is a temperature change amount calculation process or a temperature change amount calculation process.
Corresponds to the stage.

Next, at step SS4, the absolute value | SΔT | of the flaw signal SΔT is calculated in order to facilitate the flaw determination. FIG. 9D shows the absolute value | S of this flaw signal SΔT.
ΔT | is illustrated. This step SS4 corresponds to an absolute value calculation step or absolute value calculation means.

Then, in step SS5, it is judged whether or not the absolute value | SΔT | of the flaw signal SΔT exceeds a preset judgment reference value Th. This judgment reference value Th
Is a value that has been experimentally obtained in advance in order to determine the surface flaw of the conductive inspection material 10. For example, a value of about 2 ° C. is adopted. This step SS5 corresponds to the flaw determination step or the flaw determination means.

If the determination in step SS5 is negative, this routine is terminated and steps SS1 and subsequent steps are executed again, but if the determination is positive, step SS
In step 6, the flaw determination signal is output to a flaw marker or the like (not shown), and at the same time, the flaw position is stored, and then this routine is ended.

As described above, according to the present embodiment, the high frequency power supply device 24 functioning as a coil driving device drives the induction coil 18 with a high frequency current of about 100 kHz to clean the surface of the conductive inspection material 10. When heated, in such a heating process, the radiation temperature measuring device 78a,
The slit 7 formed by 78b, 78c, and 78d so as to penetrate in the thickness direction at the intermediate portion of the induction coil 18 in the width direction parallel to the moving direction of the conductive inspection material 10.
Through 6, the surface temperature of the conductive inspection material 10 is measured. That is, in this temperature measuring step, the surface temperature of the place itself, which is the surface of the conductive inspection material 10 and is induction-heated by the electromagnetic induction of the induction coil 18, is measured. As described above, since the surface temperature of the surface of the conductive inspection material 10 that is induction-heated by the electromagnetic induction of the induction coil 18, that is, the position immediately below the induction coil 18 is measured, the temperature distribution due to the flaw is measured. Since the flaw determination is performed based on the temperature detection signal ST detected within the period in which is significantly maintained, the flaw detection accuracy is high even for a non-magnetic metal having a large penetration depth δ and a temperature distribution due to the flaw is hard to appear. You can get enough. Incidentally, after passing through the induction coil 18, the temperature distribution due to the flaw is averaged by the heat conduction.

Further, according to this embodiment, the slit 76
Is formed over the entire circumference of the annular portion 70 of the induction coil 18, and as a result, is formed to be sufficiently longer than the width dimension of one of the four side surfaces of the conductive inspection material 10, so that the radiation is radiated. The temperature measuring devices 78a and 78b can measure the temperature in the entire width direction of the side surface of the conductive inspection material 10 through the slit 76, and the radiation temperature measuring devices 78c and 78d pass the corner portion of the conductive inspection material 10 through the slit 76. Can measure temperature. However, in the present embodiment, since the upper half side surface of the conductive inspection material 10 is measured at one time, the conductive inspection material 10 is rotated 180 ° and conveyed again on the remaining side surfaces. Of course, the radiation temperature measuring device 78 may be installed so as to measure all the side surfaces at one time.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other modes.

For example, in the invention of claim 1, as shown in FIG. 11, the radiation temperature measuring device 78 is obliquely arranged with respect to the induction coil 18 having no slit 76.
The same effect as that of the above-described embodiment can be obtained also by installing it toward the conductive material 10 to be inspected.

Further, although the slit 76 in the above-described embodiment is formed over the entire circumference of the annular portion 70 of the induction coil 18, it may be formed in a half circumference, or may have a rectangular cross section of the conductive test material 10. The length may correspond to the side.

Further, although the slit 76 of the above-described embodiment is formed at the center portion in the width direction of the induction coil 18, it is formed at a position deviated from the center portion in the width direction toward the conveyance direction side of the conductive inspection material 10. May be done.

Further, the induction coil 18 of the above-mentioned embodiment is
Although it is composed of the strip-shaped metal member for one round bent in an annular shape, it may be composed of an electric wire wound a plurality of times.

Further, in the powder coating apparatus 16 of the above-described embodiment, the coating gun 36 is located at a constant distance directly above the widthwise center of each side surface of the conductive test material 10. However, this position may be automatically changed as the size of the cross-sectional shape of the conductive inspection material 10 is changed.

In the above-described embodiment, the flaw is judged to be a flaw because the absolute value | SΔT | of the flaw signal exceeds the judgment reference value Th. However, the absolute value | SΔT of the flaw signal is determined.
Defects may be determined based on the fact that points where the magnitude of | exceeds the determination reference value Th continuously exist at the same width direction position for each scanning.

Further, in the above-mentioned embodiment, the high frequency drive current is supplied to the induction coil 18 or the powder 34 is applied by the application gun 36 only while the presence of the conductive inspection material 10 is detected. You may do it.

Further, the conductive material to be inspected 10 of the above-mentioned embodiment
Has a rectangular cross section, but may have a circular cross section.

The above description is merely one embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of drawings]

FIG. 1 is a plan view showing an induction heating flaw detector according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a powder coating device and an induction coil shown in FIG.

FIG. 3 is a diagram illustrating an internal structure of the powder coating apparatus of FIG.

FIG. 4 is a diagram illustrating a coating gun in the powder coating apparatus of FIG. 1 and a powder coating operation thereof.

5 is a diagram illustrating an internal structure of the powder removing apparatus of FIG.

FIG. 6 is an enlarged front view showing a part of a main part of the induction coil shown in FIG.

FIG. 7 is a side view of FIG. 6;

FIG. 8 is a view showing a radiation temperature measuring device provided in the induction heating flaw detection device of FIG. 1.

9 is a diagram showing a temperature detection signal waveform obtained from the radiation temperature measuring device of FIG. 8 and a waveform signal-processed by the operation of FIG. 10, respectively.

10 is a flowchart for explaining the operation of a flaw detection control device provided in the induction heating flaw detection device of FIG.

FIG. 11 shows an induction coil 1 according to another application example of the present invention.
8 is a diagram showing a method for measuring the surface temperature of the portion heated by 8.

[Explanation of symbols]

 10: Conductive inspection material 18: Induction coil 24: High frequency power supply device (coil driving device) 76: Slit 78: Radiation temperature measuring device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuo Ishikawa 409 Asahi-Momodai, Chita City, Aichi Prefecture (72) Inventor Taizo Yano 4-3-2 Izumira-dori, Minami-ku, Nagoya-shi, Aichi Prefecture

Claims (3)

[Claims] 1. The surface of the conductive test material is heated by generating an induction current in the conductive test material by electromagnetic induction, and the surface temperature of the conductive test material is measured. A method for inductive heating flaw detection of a conductive inspection material for detecting surface flaws of the conductive inspection material based on non-uniformity, which is a longitudinal conductive inspection object that is relatively moved in a longitudinal direction at a predetermined speed. Induction coil placed close to the side of the material,
A heating step of heating the surface of the conductive inspection material by driving with a high-frequency current, and a surface temperature of the surface of the conductive inspection material which is induction-heated by electromagnetic induction of the induction coil. A method of inductive heating flaw detection of a conductive material to be inspected, comprising: a temperature measuring step of measuring with a radiation thermometer. 2. A conductive inspected material is induced by an induction current by electromagnetic induction, the surface of the conductive inspected material is heated by the induced current, and a surface temperature of the conductive inspected material is measured.
What is claimed is: 1. An induction heating flaw detection apparatus for a conductive inspection material, which detects surface flaws in the conductive inspection material based on the nonuniformity of the surface temperature, wherein a longitudinal conductive material is moved in a longitudinal direction at a predetermined speed. Induction coil disposed near the side surface of the material to be inspected, a coil driving device for heating the surface of the conductive material to be inspected by driving the induction coil with a high frequency current, and the conductivity of the induction coil. Slits formed so as to penetrate in the thickness direction at the intermediate portion in the width direction parallel to the moving direction of the material to be inspected, and the radiation temperature for measuring the surface temperature of the electrically conductive material to be inspected through the slits in a non-contact manner. An induction heating flaw detection device for a conductive material to be inspected, comprising: a measuring device. 3. The elongated conductive material to be inspected is a rectangular material having a rectangular cross section, and the slit of the induction coil has a width of one of four side surfaces of the elongated electrically conductive material to be inspected. 3. The conductive temperature measuring device according to claim 2, wherein the conductive temperature measuring device is formed to be longer than the dimension, and the radiation temperature measuring device measures the temperature of one side surface of the conductive test material through the slit in the entire width direction. Induction heating flaw detector for inspection materials.