JPH08201308A - Surface defect detecting method for product and device thereof - Google Patents

Abstract

PURPOSE: To provide a method and a device for surely inspecting whether there is a defect or not on the surface of a product obtained by forging. CONSTITUTION: When the spot light from a light source 24 is irradiated to the surface of a product 3, the product 3 absorbs the light energy and is heated. This phenomenon does not occur on a defect portion, and the product 3 is photographed by an infrared camera 28 to be judged. An adjusting means 4 for correcting the tilt and adjusting the height is provided on a base plate 1 side fixing the product 3. The adjusting means 4 is automatically operated prior to a defect inspection, the tilt of the product 3 is corrected, the distance to the infrared camera 28 is adjusted, and measurement is invariably accurately conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a product surface defect detection method and apparatus for detecting whether or not there is a defect on the surface of a product manufactured by, for example, a forging method. It is a thing.

[0002]

2. Description of the Related Art When a product is manufactured by a forging method or the like, its surface is preferably flat, but defects such as minute cracks may occur on the surface. When defects occur on the surface in this way, even small defects cannot be used as products, and therefore individual inspections are performed. As a conventional inspection method carried out for this purpose, there is a magnetic particle flaw detection method or an electric resistance method as described in JP-A-61-240152.

In the magnetic particle flaw detection method, a magnetizing current is applied to a product made of a magnetic metal material to magnetize it, and magnetic particles made of fine particles of several microns to several tens of microns are attached to the surface of the product to visually check the attachment state. This is a method of flaw detection. On the other hand, the electrical resistance method is to detect the depth and state of the crack from the potential difference caused by applying a pair of electrodes at positions sandwiching the crack occurrence point of the product and applying an electric current to the product. .

In the above-mentioned magnetic particle flaw detection method, since it is necessary to visually inspect all the products, the efficiency is extremely poor. Some flat cylindrical surfaces can be automated with an ITV (Industrial Television) camera and image processing, but cannot be used for products with complex shapes and therefore can be manually inspected. There are many at present. Further, since the inspection is a visual inspection, the inspection accuracy tends to vary.

Further, when an attempt is made to automatically detect a product having a complicated shape by magnetic particle flaw detection, magnetic particles adhere to the edge portion other than the defect, so that it is difficult to distinguish this from the defective portion when performing image processing. There's a problem. Further, when a product having a rough surface is automatically detected by magnetic particle flaw detection, the magnetic powder mechanically adheres to the rough surface, the S / N ratio at the time of measurement deteriorates, and the defect detection efficiency decreases.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the fact that the magnetic particle flaw detection method, which is widely used at present, has the above problems, and the shape of the product to be inspected is complicated. An object of the present invention is to provide a method and a device for detecting a surface defect of a product, in which a measurement error does not occur even when the surface is rough or the surface is rough.

[0007]

According to a first aspect of the present invention, a surface of a product, which is an object to be inspected, is irradiated with spot light, and the product receives heat of the spot light to absorb and generate heat. Defects on the product surface are detected by imaging with an infrared camera the differences depending on the surface condition, and the irradiation direction of the spot light and the direction and distance of the infrared camera with respect to the direction of the product surface are adjusted to be constant values. This is a method for detecting surface defects of a product.

According to a second aspect of the invention, the light emitting means for irradiating the product, which is the object to be inspected, fixed to the base plate with the spot light, and the infrared camera for picking up the heat generated by the light emitting means are set at a predetermined angle. An optical device for holding the optical device is provided, and the optical device is provided with detection means for detecting an angle and a distance between the optical device and the product, and the detection means uses the information from the detection means as a reference value. The surface defect of the product is characterized in that the adjusting means is connected to the operating means and the adjusting means for adjusting the direction and distance of the product with respect to the optical device by the output signal of the calculating means is connected to the base plate side. It is a detection device.

[0009]

In the invention described in claim 1, when the surface of the product to be inspected has a crack or the like, the amount of heat absorbed from the spot light applied to the product is different between the crack portion and the other portion. Since they are different, there is a difference in the imaging result of the infrared camera that images them. Therefore, if this is image-processed, it is possible to determine whether the product has cracks,
If there is, it will be possible to confirm which part it is. In addition to this, the irradiation direction of the spot light with respect to the orientation of the product surface, the orientation of the infrared camera, and the distance between the infrared camera and the product surface are detected, and these orientations and distances are set to constant values according to the detected values. Since the surface of the product is irradiated with the spot light at a constant direction and distance, and the direction and distance of the heat-generating light are also constant, the measurement can always be performed under constant conditions.

According to the second aspect of the present invention, the data of the defect-free product attached to the base plate in advance is stored in the storage device of the arithmetic means. Next, the product to be inspected is fixed to the base plate, and the direction and distance between the optical device and the product are measured by the detection means provided in the optical device.
The data is compared to the previously taken data of the defect-free product and the adjusting means is activated so that they match. After this adjustment, the surface of the product is irradiated with spot light from the light emitting means, and an image is taken with an infrared camera.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 denotes a base plate, which is used to fix a product 3, which is an object to be inspected, to the upper surface by a clamp 2. Product 3
Is to be inspected for a defect on the surface by the structure described later. The base plate 1 has a rectangular shape, and is supported by the position changing plate 5 via adjusting means 4 at four corners. The position changing plate 5 is supported by the base 7 via the motor mounting plate 6.

A motor 8 is mounted on two intersecting surfaces of the motor mounting plate 6 so that the position of the position changing plate 5 can be changed in the horizontal plane. As a specific configuration of this portion, for example, a male screw is engraved on the decelerated output shaft of the motor 8, and a female screw with which this male screw is screwed is engraved on the position changing plate 5 side so that they are mutually screwed. You can think of what suits you. With such a structure, when the motors 8 are operated, the position changing plate 5 moves in the horizontal plane according to the rotation thereof. Therefore, by appropriately operating the two motors 8, the position change can be performed. The plate 5 can be changed to any position with respect to the base 7.

The adjusting means 4 comprises an actuator 9 and a piezoelectric element 10, as shown in FIG. A rod 13 having a rack gear 12 partially engraved therein is supported in the cylinder 11 of the actuator 9 so as to be able to move up and down. A pinion gear 16 engraved on the output shaft 15 of the motor 14 is screwed onto the rack gear 12. are doing. As the motor 14, a stepping motor or a servo motor can be used. An encoder (not shown) is provided inside the cylinder 11 of the actuator 9 so that the protrusion amount of the rod 13 can be electrically detected.

A flange 17 is provided on the upper end of the rod 13 of the actuator 9, and the piezoelectric element 10 is mounted on the flange 17. A plate 18 is provided above the piezoelectric element 10, and the base plate 1 is supported via the plate 18.

At a suitable distance above the product 3, an optical device 19 used for detecting a defect on the surface of the product 3 is firmly suspended by a column 20 so as not to move. . As shown in FIG. 3, the optical device 19 is composed of a top plate 21 and side plates 22 and 23, and the side plates 22 and 23 are shaped so that their lower ends approach each other at a predetermined angle.

On one side plate 22 of the optical device 19, a light source 24 as a light emitting means and two condenser lenses 25, 26 are provided.
Are attached to form a light emitting means 27 for irradiating the surface of the product 3 with spot light. The other side plate 2
3 has a wavelength sensitivity of 2 to image the reflected light of the spot light.
An infrared camera 28 of about 5 μm is attached. An angle α is maintained between the optical axis of the light emitting means 27 and the condensing axis of the infrared camera 28, and the height of the optical device 19 is adjusted so that the intersecting point is on the surface of the product 3. Is set. Further, in this case, as shown in FIG. 1, a predetermined angle β is maintained between the focusing axis of the infrared camera 28 and the surface of the product 3.

Inside the top plate 21 of the optical device 19, a two-dimensional PSD (semiconductor position detector capable of measuring in a plane range) 29 is attached as a detecting means for detecting an angle and a distance with respect to the surface of the product 3. . This two-dimensional PSD
Reference numeral 29 is known as a device that receives a light spot and detects its position. The two-dimensional PSD 29 has a rectangular shape, and light emitting diodes (which may be laser light emitting bodies) 30 are attached to four locations on the outer periphery thereof. The light of the light emitting diode 30 is directed to the product 3, is reflected by hitting the product 3, and the reflected light enters the two-dimensional PSD 29. The two-dimensional PSD 29 and the light emitting diode 30 face the surface of the product 3 and constitute a detecting means 31 for detecting an angle and a distance with respect to the surface of the product 3.

Returning to FIG. 1, description will be made. Reference numeral 32 is a control circuit for the entire apparatus, which receives various signals and outputs a predetermined output signal. A position detection command signal is output from one output terminal of the control circuit 32 and sequentially input to the lighting circuit 33. Sequential lighting circuit 33
Sends its signal to four light emitting diodes 30,
The light emitting diodes 30 are sequentially turned on, and a synchronization signal thereof is sent to the position detection circuit 34 at the next stage.

The position detection circuit 34 receives signals from the lighting circuit 33 in sequence and the output signal of the two-dimensional PSD 29, obtains signals of the position and distance of the product 3 with respect to the position of the optical device 19, and calculates the signals. Is input to the angle / distance calculation circuit 35. The angle / distance calculation circuit 35 calculates the position and distance of the product 2 with respect to the position of the optical device 19 in relation to the reference value based on the signal from the position detection circuit 34, and sends the resulting signal to the control circuit 32. Is.

In addition to the above, the control circuit 32 includes an image processing device 36, an adjusting means control circuit 37, and a motor drive circuit 38.
Are connected to and receive signals from the control circuit 32. The input side of the image processing device 36 is connected to the output side of the infrared camera 28 described above. The actuator 9 and the piezoelectric element 10, which are adjusting means, are connected to the adjusting means control circuit 37. The aforementioned motor 8 is connected to the motor drive circuit 38.

FIG. 4 shows the internal structure of the position detection circuit 34. The position detection circuit 34 includes an amplifier 39
And A / D conversion board (8 bit or 16 bit) 4
0 and an interface (GP-IB board or Ethernet board) 41. Amplifier 3
Reference numeral 9 amplifies the analog signal from the light emitting diode 30 input to the input terminals, and outputs it to the A / D conversion board 40 while maintaining a predetermined interval. The A / D conversion board 40 converts the signal into a digital signal and outputs an output signal to the angle / distance calculation circuit 35 via the interface 41.

FIG. 5 shows an angle / distance calculation circuit 3
5 is an internal configuration. At this angle / distance 35, an interface (GP-IB board or Ethernet board) 42, a ROM circuit 43, a RAM circuit 44 and C
A PU (Central Processing Unit) 45 is provided, and these are connected by a bus 46. The ROM circuit 43 stores a conversion formula and an operation program of the CPU 45,
The RAM circuit 44 stores the angle and distance signals of the product 2 that have entered via the interface 42.

FIG. 6 shows the internal structure of the control circuit 32. The control circuit 32 includes an interface (GP-IB board or Ethernet board) 4
7, a ROM circuit 48, a RAM circuit 49, a CPU 50, and a parallel interface 51 are provided, and these are connected by a bus 52. ROM circuit 48, R
The AM circuit 49 and the CPU 50 have the interface 4
The signal input to 7 is subjected to predetermined processing and output from the parallel interface 51. The signals output from the parallel interface 51 are a position detection command signal, an inspection command signal, an actuator control command signal, and a piezoelectric element control command signal. The input signals are a measurement determination result signal, an actuator control completion signal, and a piezoelectric element control completion signal.

FIG. 7 shows an adjusting means control circuit 37.
It is the internal circuit of. The adjusting means control circuit 37 includes an interface (GP-IB board or Ethernet board) 53, a D / A conversion board 54, and a control CP.
A U55 and an amplifier 56 are provided. And CP
The U55 receives a control command signal and outputs a control completion signal when the control is completed. The amplifier 56 receives a signal from the CPU 55 and the D / A conversion board 54, amplifies the signal to a predetermined power, and drives each of the four actuators 9 and the piezoelectric element 10.

When the device thus constructed is operated, the surface defect detection method for a product according to claim 1 is realized. The object of the present invention is to detect whether or not defects are present on the surface of the product 3 and for that purpose the product 3
The surface of the product is irradiated with spot light, and it is detected that the light energy is absorbed by the product 3 to generate heat in the defect-free portion of the product 3, and the light energy is not absorbed in the defect portion (which can be considered as a groove). Since it does not generate heat, it is a method of determining whether or not there is a defective portion in the product 3 by detecting this. Then, the light transmission / reception angle and the distance are properly set so that the defective portion can be detected correctly. The method will be described.

The procedure is performed in the order shown in the flowchart of FIG. That is, when starting in step S1, the angle of the product 3 is detected in the following step S2,
In the following step S3, the movement amount of the actuator 9 is calculated. Next, angle adjustment and distance adjustment are performed at the same time (steps S4 and S5), and after that, defect detection is performed (step S6), and the process ends at step S7).

In the work, first, as a preparation, a defect-free reference product 3 is attached to the base plate 2 and is properly leveled. Then, the surface of the product 3 forms an angle β with respect to the converging axis of the infrared camera 28 of the optical device 19 located above.
Set so that In order to obtain the angle β, the lighting circuits 33 are sequentially operated, and the reflected light of the light emitting diodes 30 that are turned on one by one is imaged on the two-dimensional PSD 29.

The position information of each point imaged on the two-dimensional PSD 29 is output as a plus or minus voltage signal for each X and Y coordinate with respect to the center of the two-dimensional PSD 29.
The XY coordinate signal from the two-dimensional PSD 29 is amplified by the amplifier 39 of the position detection circuit 34 and then converted into digital data by the A / D conversion board 40. The digitally converted data is transferred to the angle / distance calculation circuit 35 through the interface 41, and the RAM circuit 4
4 is stored.

Next, the product 3 to be inspected is attached to the base plate 2
2D PSD29 by the same method as above.
To obtain the XY coordinate signals. This signal is transferred to the angle / distance calculation circuit 35, where the CPU 45 outputs RA
It is compared with the data of the reference XY coordinates (position in the horizontal plane) stored in the M circuit 44. After the comparison, the amount of each point in the Z direction (height direction) is calculated from the difference according to the principle of triangulation. From the displacement amount in the Z direction calculated in this way, the CPU 45 in the angle / distance calculation circuit 35
The inclination of the product 3 and the distance to the infrared camera 28 will be calculated. When inspecting other parts of the product 3, the motor 8 is operated to move the upper part from the position changing plate 5.

The data calculated in this way is transferred to the control circuit 32 via the interface 42.
This data is given to the CPU 50 in the control circuit 32, and the actuator 9 and the piezoelectric element 10 for making the surface of the product 3 parallel to the two-dimensional PSD 29 of the optical device 18.
Is calculated. The calculated data is transferred from the parallel interface 51 to the lifting / lowering means control circuit 37. The transferred data is adjusted by the adjusting means control circuit 3
It is converted into an analog signal by the D / A conversion board 54 in 7 and given to each of the four actuators 9 and the piezoelectric elements 10 via the CPU 55 and the amplifier 56, and these are operated to make the surface of the product 3 two-dimensional PSD 29. Parallel to.

In this case, when the amount of movement for adjustment is large, the actuator 9 first operates to make an approximate adjustment, and then the piezoelectric element 10 makes a fine adjustment. It will be done at the same time.
Further, theoretically, in order to correct the inclination of the product 3, one of the four adjusting means 4 is largely moved so that when the inclination is corrected, all the adjusting means 4 are simultaneously operated. I will adjust the distance by
Actually, the adjusting means 4 at four locations are simultaneously operated to make an instantaneous adjustment.

The actuator 9 and the piezoelectric element 10 are actuated to correct the inclination of the product 3 so that the surface of the product 3 becomes parallel to the two-dimensional PSD 29 and the two-dimensional PSD 2
When the distance to 9 is corrected to a constant value, the adjusting means control circuit 37 issues an angle adjustment completion signal to the image processing device 36. After receiving this signal, the image processing device 36 takes in the image from the infrared camera 28, processes it and processes it.
It is judged whether or not there is a defect on the surface, and the result is sent to the control circuit 32 to end a series of inspection work. When a plurality of products 3 are placed on the base plate 1, 1
After the inspection of the individual pieces, the motor 8 is operated to move the upper portion from the position changing plate 8 by an appropriate distance to move the next product 3 to a predetermined position, and the same inspection is performed.

In the above-described embodiments, the position detecting circuit, the angle / distance calculating circuit, the control circuit, and the adjusting means control circuit are described as using independent CPUs. CPU is 1
You can make it in time with individual items. Further, in the actuator shown in FIG. 2, a rack gear and a pinion gear are used, but this may be changed to one using a worm gear and a worm wheel. If you change like this,
Even if load is applied to the rod side of the actuator,
Therefore, the rod does not move.

[0034]

The present invention is a method and apparatus for detecting a surface defect of a product configured as described above, and is for inspecting a defect after adjusting the orientation (angle) of the product. When the inspections are performed successively, unevenness does not occur in each, and the inspections can be performed accurately. Further, not only the angle between the surface of the product and the focusing axis of the infrared camera can be adjusted, but also the distance can be controlled, so that the product having a complicated shape can be dealt with.
Furthermore, since it is not necessary to spray magnetic powder or magnetic powder liquid as in the magnetic particle flaw detectors that have been often used in the past, it is possible to detect defects in a narrow space.

[Brief description of drawings]

FIG. 1 is a system diagram showing a partial perspective view of a system according to the present invention.

FIG. 2 is a perspective view showing a portion of an actuator and a piezoelectric element in FIG.

FIG. 3 is a perspective view of the optical device in FIG.

FIG. 4 is a block diagram showing a configuration of a position detection circuit.

FIG. 5 is a block diagram showing a configuration of an angle / distance calculation circuit.

FIG. 6 is a block diagram showing a configuration of a control circuit.

FIG. 7 is a block diagram showing a configuration of an adjusting means control circuit.

FIG. 8 is a flow chart showing the steps of the invented method.

[Explanation of symbols]

 1 Base Plate 3 Product 4 Adjusting Means 9 Actuator 10 Piezoelectric Element 14 Motor 19 Optical Device 24 Light Source 25 Condensing Lens 26 Condensing Lens 27 Light Emitting Means 28 Infrared Camera 29 Two-dimensional PSD 30 Light Emitting Diode 31 Detecting Means 32 Control Circuit 34 Position Detection Circuit 35 Angle / distance calculation circuit 36 Image processing device 37 Adjustment means control circuit

Claims (2)

[Claims] 1. A surface of a product to be inspected is irradiated with spot light, and an infrared camera captures an image of the amount of heat that the product absorbs and heats upon irradiation of the spot light, depending on the surface condition. The method for detecting a surface defect of a product is characterized by detecting a defect on the surface of the product and adjusting the irradiation direction of the spot light and the direction and distance of the infrared camera with respect to the direction of the surface of the product to be constant values. 2. An optical device for holding at a predetermined angle a light emitting means for irradiating a product, which is an object to be inspected, fixed to a base plate with spot light, and an infrared camera for picking up the heat generated by the light emitting means, The optical device is provided with detection means for detecting an angle and a distance between the optical device and the product, and the detection means is provided with arithmetic means for calculating information from the detection means in relation to a reference value. A surface defect detection device for a product, which is connected to the base plate, and is provided with adjusting means for adjusting a direction and a distance of the product with respect to the optical device according to an output signal of the computing means.