JPH0129256B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a linear groove-like flaw detection device.

Generally, when producing a veneer veneer, if foreign matter adheres to the cutting knife or the knife has a chip, knife marks will occur on the veneer veneer. Therefore, in order to detect this knife mark, the following device has conventionally been used.
That is, as shown in FIG. 1, while conveying the veneer veneer 1 in the direction of arrow A, the white light emitted from the white light source 3 is converted into line light 5 by the cylindrical lens 4, and the veneer veneer 1 is conveyed in the direction of arrow A. A knife mark scratch 6 on the plate 1 is irradiated, and the diffusely reflected light generated by the knife mark scratch 6 is transmitted through a slit 7, a cylindrical lens 8, and a slit 9 to a photomultiplier 1.
Lead to 0. FIG. 2 shows an output signal waveform diagram of the photomultiplier 10, in which a flaw detection waveform 11 is generated when a knife mark flaw 6 approaches the irradiation position of the line light 5. Therefore, by detecting this flaw detection waveform 11 with a flaw detection circuit, the knife mark flaw 6 is detected.
Detects the presence of.

In this case, as shown in FIG. 2, the change in light intensity due to the knife mark scratch 6 is minute, so in order to enable scratch detection, both slits 7 and 9 and the cylindrical lens 8 must be aligned in the longitudinal direction of the knife mark scratch. It is necessary to precisely match the longitudinal direction of 6.
(The veneer veneer 1 is formed by slicing the fritches 12 with a knife 13, as shown in FIG.
Therefore, the angle θ of the knife mark scratch 6 shown in FIG. 1 with respect to the side of the veneer veneer 1 is a complementary angle to the above-mentioned angle α. ) Therefore, conventionally, veneer veneer 1
On the assumption that the veneer veneer 1 is conveyed parallel to the conveyor 2, the entire optical system shown in FIG. 7, 9, Photomaru 10) is rotationally controlled by a pulse motor,
The longitudinal direction of the line light 5 is made to exactly match the longitudinal direction of the knife mark scratch 6. However, this method requires very strict conveyance accuracy, and if the parallelism between the conveyor 2 and the veneer veneer 1 is lost, the S-N ratio of knife mark flaw detection, that is, the flaw detection accuracy, will drop significantly. had.

Accordingly, an object of the present invention is to provide a linear groove-like flaw detection device that can accurately detect linear groove-like flaws on the surface of a strip-shaped inspection object without being affected by conveyance accuracy.

An embodiment of the present invention will be explained using FIGS. 4 to 6. That is, this linear groove-like flaw detection device includes a flaw detection head 14 shown in FIG. 4, which is equipped with the entire optical system (white light source 3, cylindrical lenses 4, 8, slits 7, 9, photomul 10) shown in FIG. is held rotatably around a vertical shaft 17 by a pulse motor 16 above the conveyor 15, and a board edge detection sensor 18, a laser oscillator 19, and a scanner 2 are installed before the flaw detection head 14 is transported.
0, a line sensor 21 and a time/pulse conversion device 22 are arranged. In this case, the line sensor 21
is formed by arranging a plurality of light receiving elements on a straight line.

Detection of knife marks by this device is performed as follows. That is, when the veneer veneer 23 shown in FIG. 5 is conveyed in the direction of arrow B by the conveyor 24, the front end 23a (the fifth
) is detected by the board edge detection sensor 18, and the scanner 20 scans the laser beam 25 from the laser oscillator 19 onto the line sensor 21, and the line sensor 21 is The output signal is sent to a time-to-pulse conversion device 22.

FIG. 6a shows an output signal waveform diagram of the line sensor 21 when passing point C, and FIG. 6b shows an output signal waveform diagram of the line sensor 21 when passing point D. In both of these waveform diagrams, the signal falling portions 26 and 27 are caused by the laser beam 25 being blocked by the veneer veneer 23. Therefore, as shown in FIG. 5, when the longitudinal direction of the veneer veneer 23 is obliquely viewed with respect to the conveyor conveyance direction (arrow B direction), the shading start time of both signal waveform diagrams changes depending on the inclination angle. Since there is a difference between t ₁ and t ₂ , the difference between the two shading start times (t = t ₂ - t ₁ ) is calculated by the time/pulse converter 22, and the difference is calculated in the conveyor transport direction of the veneer veneer 23 (arrow B direction) is detected. Then, depending on this conveyance deviation angle, time and
A forward rotation pulse or a reverse rotation pulse is sent from the pulse conversion device 22 to the pulse motor 16 to control the rotation of the pulse motor 16, and the longitudinal direction of the line light projected from the flaw detection head 14 is detected by the knife mark flaw 28.
(Fig. 5) to match the longitudinal direction.

In this way, the conveyance deviation angle in the longitudinal direction of the veneer veneer 23 with respect to the conveyor conveyance direction (arrow B direction) is detected, and the flaw detection head 14 is rotationally controlled in accordance with the conveyance deviation angle to perform flaw detection. A stable signal-to-noise ratio for knife mark flaw detection can be obtained without being affected by the conveyance accuracy of the veneer veneer 23.

In addition, in the above embodiment, the veneer veneer 23
The conveyance deviation angle with respect to the conveyor conveyance direction (direction of arrow B) was determined from the difference between the start times t ₁ and t ₂ of the laser beam 25 being blocked by the veneer veneer 23, but the difference between the times t ₃ and t ₄ when the laser beam 25 was blocked by the veneer veneer 23 was determined. It can also be found from In addition, instead of the laser beam 25, a belt-shaped inspection light beam whose longitudinal direction is perpendicular to the conveyor conveyance direction (arrow B direction) is irradiated onto the line sensor 21 to pass the front and rear ends of the veneer veneer 23. The conveyance deviation angle of the veneer veneer 23 may be detected from the difference in the shielding position of both the inspection light beams at the time. Further, in the above embodiment, the knife mark flaw 28 on the veneer veneer 23 is detected, but the present invention can be widely used to detect a linear groove-like flaw having a predetermined angle with respect to the band edge of a band-shaped object to be inspected. is possible.

As described above, the linear groove-like flaw detection device of the present invention is held above a conveyor so as to be rotatable around a vertical axis, and irradiates a line light onto the surface of a strip-shaped inspection object on the conveyor, and detects the reflected light from the inspection object. A flaw detection means for detecting the presence of a linear groove-like flaw having a predetermined angle with respect to the band edge, and a flaw detection means arranged before the conveyance of this flaw detection means, and a flaw detection means arranged on a line perpendicular to the conveyance direction of the conveyor when the strip-shaped object to be inspected passes the front and rear ends. An inspection light irradiation means for irradiating the inspection light beam, a light receiving means for receiving both of the inspection light beams, and a conveyor transport direction in the longitudinal direction of the strip-shaped inspection object due to the difference in the shielding position of both inspection light beams received by the light receiving means due to the strip-shaped inspection object. a conveyance deviation angle detection means for detecting a conveyance deviation angle with respect to the conveyance deviation angle; and a rotation control means for controlling the rotation of the flaw detection means so that the line light coincides with the linear groove-like flaw in accordance with the output signal of the conveyance deviation angle detection means. This has the effect that linear groove-like flaws on the surface of the strip-shaped inspection object can be detected with high accuracy without being affected by conveyance accuracy.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a conventional example, Fig. 2 is an output signal waveform diagram from a photomultiplier, Fig. 3 is a perspective view showing the positional relationship between the flitch and knife, and Fig. 4 is a perspective view of an embodiment of the present invention. , FIG. 5 is a plan view showing the laser beam scanning position on the veneer veneer, and FIGS. 6a and 6b are output signal waveform diagrams from the line sensor, respectively. 14...Flaw detection head (flaw detection means), 15...Conveyor, 16...Pulse motor (rotation control means),
17... Vertical axis, 19... Laser oscillator (inspection light irradiation means), 20... Scanner (inspection light irradiation means),
21...Line sensor (light receiving means), 22...Time/
Pulse conversion device (conveyance deviation angle detection means), 23...
Veneer veneer (band-shaped inspection object), 28...knife mark scratches (straight groove-shaped scratches).

Claims (1)

[Claims] 1 It is held above the conveyor so as to be rotatable around a vertical axis, and irradiates a line light onto the surface of the strip-shaped inspection object on the conveyor, and uses the reflected light to detect the presence of linear groove-like flaws with a predetermined angle to the edge of the inspection object strip. a flaw detection means for detecting flaws; an inspection light irradiation means disposed before the conveyance of the flaw detection means for emitting an inspection light beam on a line perpendicular to the conveyor conveyance direction when the strip-shaped object to be inspected passes the front and rear ends; and both of the above-mentioned inspection light beams. a conveyance deviation angle detection means for detecting a conveyance deviation angle in the longitudinal direction of the strip-shaped inspection object with respect to the conveyor conveyance direction from the difference in the shielding position of both inspection beams received by the light-receiving means by the strip-shaped inspection object; A linear groove-like flaw detecting device comprising: rotation control means for rotationally controlling the flaw detecting means so that the line light coincides with the linear groove-like flaw according to an output signal of the conveyance deviation angle detecting means.