JP2009078356A - Plywood inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To previously detect a flaw bringing about the appearance failure of a product. <P>SOLUTION: Plywood 2 is uniformly heated by a heating device 7 and the surface temperature distribution of the plywood 2 after heating treatment is measured by an inspection device 8. On the basis of the surface temperature distribution of the plywood 2, it is judged whether the composite veneer of and incide the second layer from the surface of the plywood 2 has a flaw or not. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for inspecting plywood constituting a wooden flooring.

The wooden flooring consists of plywood and sliced veneer (wooden veneer veneer) that is press bonded to the plywood surface. The grain direction of the fourth layer is formed by laminating a plurality of single plates in which the grain direction is orthogonal, such as the width direction. The sliced veneer is composed of a single veneer, but each layer of plywood cannot be composed of a single veneer, so it is composed of a composite veneer formed by joining the veneers. Yes. In such a wooden floor material, defects such as voids, nests, and decay may occur in the plywood. From such a background, before bonding the sliced veneer, by pressing the surface of the plywood with a pressure roller, and detecting the behavior of the pressure roller generated in the pressing direction by relatively moving the plywood and the pressure roller A technique for detecting defects in a plywood has been proposed (see Patent Document 1).
Japanese Patent Laid-Open No. 9-11203

  A wooden flooring is finished into a product by coloring the sliced veneer surface after actual processing. The inventors of the present invention have conducted extensive research, and as a result, when there are voids, nodes, different tree species, and joints in the composite single plate after the second layer from the plywood surface, It was found that temperature unevenness occurred on the surface of the plywood due to the difference and thermal conductivity difference caused by the joints, and this temperature unevenness caused the appearance of the product such as uneven gloss when coloring the surface of the sliced veneer. More specifically, since the silica component (matte erasing material) contained in the paint has a property of aggregating in a high temperature region, when temperature unevenness exists on the surface of the plywood, uneven glossiness occurs and causes a product appearance defect. However, according to the conventional inspection apparatus, it has been impossible to detect a defect in the composite single plate after the second layer from the plywood surface causing such a product appearance defect.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for inspecting a plywood that can detect a defect causing a product appearance defect.

  A plywood inspection method according to the present invention is a plywood inspection method configured by laminating a plurality of composite single plates formed by joining single plates, a heating step for uniformly heating the plywood, A measurement step for measuring the temperature distribution on the plywood surface after the heating step, and a determination step for determining whether or not the composite single plate after the second layer from the plywood surface has a defect based on the temperature distribution on the plywood surface. Have.

  According to the method for inspecting a plywood according to the present invention, since it is determined whether or not there is a defect in the composite single plate after the second layer from the plywood surface based on the temperature distribution on the surface of the plywood, the defect that causes a defective appearance of the product. It can be detected in advance.

  The present invention can be applied to a defect inspection process for a plywood constituting a wooden flooring 1 as shown in FIG. Hereinafter, a plywood inspection method according to an embodiment of the present invention will be described in detail with reference to the drawings. 1 comprises a plywood 2 and a slice veneer 3 that is press-bonded to the plywood 2. The plywood 2 is formed by joining the veneers 4a at the joint 5 as shown in FIG. The composite single plate 4 is formed by stacking a plurality of sheets. This wooden flooring 1 is finished into a product by performing a color process on the surface of the slice veneer 3 after actual processing.

[Plywood inspection equipment]
The plywood inspection method according to the embodiment of the present invention is performed using the inspection apparatus shown in FIG. The inspection apparatus shown in FIG. 3 includes a belt conveyor 6 that conveys the plywood 2 before press-bonding the sliced veneer 3 in the direction of the arrow, and an IR heater that uniformly heats the entire plywood 2 conveyed from the belt conveyor 6. A heating device 7 and an inspection device 8 for inspecting the plywood 2 for defects are provided. As shown in FIG. 4, the inspection device 8 includes an infrared camera 9 that captures a thermal image of the plywood 2 heated by the heating device 7, and an image capture that captures the thermal image of the plywood 2 by controlling the operation of the infrared camera 9. The image capture device 10, the image processing device 11 that performs image processing to be described later on the thermal image captured by the image capture device 10, and the defect discharge that determines the defect of the plywood 2 based on the image processing result by the image processing device 11. And a control device 12. The heating temperature of the heating device 7 is configured to be settable by an inspector. In this embodiment, the heating temperature is set to a temperature higher than the outside air temperature. The infrared camera 9 is disposed in the vicinity of the outlet of the heating device 7 so as to capture a thermal image of the plywood 2 immediately after being heated by the heating device 7. By taking a thermal image of the plywood 2 using the infrared camera 9, the surface temperature of the plywood 2 can be measured in a non-contact manner. Moreover, since a thermal image can be image-processed by a binarization process, the defect of the plywood 2 can be inspected at high speed while the plywood 2 is conveyed by the belt conveyor 6.

[Plywood inspection method]
Hereinafter, a plywood inspection method according to the first to fourth embodiments of the present invention using the inspection apparatus will be described.

[First Embodiment]
In the plywood inspection method according to the first embodiment of the present invention, first, the infrared camera 9 captures a thermal image of the plywood 2 (see FIG. 5), and the image capturing device 10 captures the thermal image of the plywood 2. The image is output to the image processing apparatus 11. Next, the image processing apparatus 11 scans the entire thermal image 20 to identify the pixel position P1 indicating the maximum temperature T _MAX from the thermal image 20 as shown in FIG. 6A, and then from the pixel position P1. By scanning in the width direction of the plywood 2, the pixel position P2 indicating the temperature near the maximum temperature T _MAX is specified as shown in FIG. 6B. Next, after the image processing apparatus 11 defines a straight line L1 passing through the pixel positions P1 and P2, as shown in FIG. 6C, a thermal image is taken from the straight line L1 in the length direction (+ direction, − direction) of the plywood 2. By scanning 20, the pixel position indicating the minimum temperature T _MIN is specified. The poor emission control device 12 calculates a difference value ΔT1 of the distance ΔD and the highest temperature _{T MAX} and the minimum temperature _{T MIN} between the pixel position indicating the minimum temperature _{T MIN} 7, distance ΔD is a predetermined value D _When the difference value ΔT1 is equal to or less than _TH1 and the difference value ΔT1 is equal to or greater than the predetermined value _TTH1, it is determined that there is a defect that causes a defective product appearance from the surface of the plywood 2 to the second and subsequent composite single plates 4.

If there are voids or joints 5 in the composite veneer 4 of the second layer from the surface of the plywood 2, it is difficult for heat to be transferred to the composite veneers 4 after the third layer due to the voids or joints 5. As a result, the temperature of the surface of the plywood 2 immediately above the gap and the joint 5 becomes higher than that of other regions. Therefore, according to such a method for inspecting plywood, it is possible to detect a defect in the composite veneer 4 subsequent to the second layer from the surface of the plywood 2 causing a defective appearance of the product at high speed by a simple process. Even if the difference value ΔT1 is greater than or equal to the predetermined value T _TH1 , gloss unevenness is found when the distance ΔD is greater than or equal to the predetermined value D _TH1 , in other words, when the high temperature region is distributed with a width greater than or equal to the predetermined value D _TH1. In this embodiment, a defect that causes a product appearance defect only when the distance ΔD is equal to or less than the predetermined value D _TH1 and the difference value ΔT1 is equal to or greater than the predetermined value T _TH1. Judge that there is.

[Second Embodiment]
In the plywood inspection method according to the second embodiment of the present invention, first, the infrared camera 9 captures the thermal image 20 of the plywood 2 and the image capture device 10 captures the thermal image 20 of the plywood 2 and an image processing device. 11 is output. Next, the image processing apparatus 11 scans the entire thermal image 20 to calculate the average temperature T _AV on the surface of the plywood 2 and specify the maximum temperature T _MAX . The poor emission control device 12 calculates a difference value ΔT2 of the average temperature T _AV between the maximum temperature T _MAX, the composite veneer of the second layer after the plywood 2 surface when the difference value ΔT2 is the predetermined value T _TH2 or more 4 is determined to have a defect that causes a defective product appearance. According to the inspection method of the plywood, so determining the presence or absence of a defect with the average temperature T _AV plywood 2 surface defects while suppressing the influence of variations in temperature of the entire plate 2 surface by changes in the surrounding environment The presence or absence of can be determined stably.

[Third Embodiment]
In the plywood inspection method according to the third embodiment of the present invention, as shown in FIG. 10, first, the defective discharge control device 12 has the highest temperature measured by the plywood inspection method according to the second embodiment. A region G including a point on the plywood surface P3 indicating a temperature within a predetermined temperature range from the pixel position P1 indicating T _MAX and the maximum temperature T _{MAX is} set by patterning a square or circular pattern, and set In the region G, the point where the temperature difference from the average temperature T _{AV on the} surface of the plywood 2 is equal to or greater than a predetermined value T _TH3 is equal to or greater than a specified number N _TH1 and the area S of the region G is equal to or less than the predetermined value S _TH1 It is determined that there is a defect in the second and subsequent composite single plates from the plywood surface. At this time, as shown in FIG. 11, a point (surface temperature T _MIN ) smaller than the average temperature T _AV of the plywood 2 surface by a predetermined value ΔT3 or more is a specified number N _TH2 or more, and the area S of the region G is a predetermined value. When it is _STH1 or less, it can also be determined that there is a defect derived from a node in the composite single plate after the second layer from the surface of the plywood 2.

[Fourth Embodiment]
In the plywood inspection method according to the fourth embodiment of the present invention, first, the infrared camera 9 does not capture the thermal image 20 from directly above the plywood 2 as shown in FIG. As shown in (b), the thermal image is taken from the direction in which the thermal image 20 on the side surface of the plywood 2 can be taken simultaneously with the surface of the plywood 2 (in the example shown in FIG. 12B, the imaging direction is 30 degrees with respect to the surface of the plywood 2). 20 is measured. Next, the image processing apparatus 11 scans the entire thermal image 20 on the surface and side surfaces of the plywood 2 to identify the maximum temperature regions R1 and R2 on the surface of the plywood 2 and the side surfaces of the plywood 2 as shown in FIG. Then, the defective discharge control device 12 defines a straight line L2 in the plywood width direction passing through the maximum temperature region R1 on the surface of the plywood 2, and when the maximum temperature region R2 on the side surface of the plywood 2 exists on the straight line L2, from the surface of the plywood 2 It is determined that the composite single plate after the second layer is defective. When the gap formed in the composite veneer 4 is a certain length (150 mm) or more in the width direction, the appearance becomes poor when finished to a wooden flooring, but this gap is clogged with adhesives and chips. Therefore, the air gap may not be detected from the thermal image 20. Therefore, according to such a plywood inspection method, when the maximum temperature region R2 on the side surface of the plywood 2 exists on the straight line L2, it is determined that there is a defect in the composite single plate after the second layer from the plywood 2 surface. Even if the defect cannot be determined from the thermal image 20, the defect region R3 existing between the maximum temperature region R1 and the maximum temperature region R2 can be estimated.

  As mentioned above, although embodiment which applied the invention made by the present inventors was described, this invention is not limited by description and drawing which make a part of indication of this invention by this embodiment. That is, it is needless to say that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

It is a perspective view which shows the structure of the wooden floor material used as embodiment of this invention. It is a perspective view which shows the structure of the composite single board which forms the plywood shown in FIG. It is a schematic diagram which shows the structure of the inspection apparatus of the plywood used as embodiment of this invention. It is a block diagram which shows the internal structure of the test | inspection apparatus shown in FIG. It is a figure which shows an example of the thermal image of the plywood imaged with the test | inspection apparatus shown in FIG. It is a schematic diagram for demonstrating the inspection method of the plywood used as the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the inspection method of the plywood used as the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the inspection method of the plywood used as the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the inspection method of the plywood used as the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the inspection method of the plywood used as the 3rd Embodiment of this invention. It is a schematic diagram for demonstrating the inspection method of the plywood used as the 3rd Embodiment of this invention. It is a schematic diagram for demonstrating the inspection method of the plywood used as the 4th Embodiment of this invention. It is a schematic diagram for demonstrating the inspection method of the plywood used as the 4th Embodiment of this invention.

Explanation of symbols

1: Wood flooring 2: Plywood 3: Slice veneer (wood grain veneer veneer)
4: Composite single plate 4a, 4b: Single plate 5: Joint 6: Belt conveyor 7: Heating device 8: Inspection device 9: Infrared camera 10: Image capturing device 11: Image processing device 12: Defect discharge control device 20: Thermal image

Claims (6)

A plywood inspection method configured by laminating a plurality of composite single plates formed by joining single plates,
A heating step for uniformly heating the plywood;
A measuring step for measuring the temperature distribution of the plywood surface after the heating step;
And a determination step of determining whether or not the second and subsequent composite single plates are defective from the surface of the plywood based on the temperature distribution on the surface of the plywood. In the inspection method of the plywood according to claim 1,
The measuring step includes a step of measuring a maximum temperature of the plywood surface and a distribution width thereof, and the determination step includes a composite unit of the second and subsequent layers from the plywood surface when the distribution width is equal to or less than a first predetermined value. A method for inspecting plywood, comprising a step of determining that a board is defective. In the inspection method of the plywood of Claim 1 or Claim 2,
The measurement step includes a step of measuring a maximum temperature and an average temperature of the plywood surface, and the determination step is performed from the plywood surface when a temperature difference between the maximum temperature and the average temperature is a second predetermined value or more. A method for inspecting plywood, comprising the step of determining that the composite veneer after the first layer is defective. In the inspection method of the plywood according to claim 3,
The determination step sets a region including a point on the plywood surface showing the highest temperature and a point on the plywood surface showing a temperature within a third predetermined temperature range from the highest temperature, and the average is set in the set region. When the point where the temperature difference from the temperature is equal to or greater than the third predetermined value is equal to or greater than the fourth predetermined value, and the area of the region is equal to or smaller than the fifth predetermined value, the composite veneer after the second layer from the plywood surface A method for inspecting plywood, comprising a step of determining that there is a defect. In the inspection method of the plywood according to any one of claims 1 to 4,
The said measuring process has a process of measuring the temperature of a plywood side surface simultaneously with the plywood surface, The inspection method of the plywood characterized by the above-mentioned. In the inspection method of the plywood according to claim 5,
The measuring step includes a step of measuring the maximum temperature of the plywood surface and the side surface of the plywood, and the determining step defines a straight line in the width direction of the plywood passing through a point indicating the maximum temperature on the surface of the plywood, A method for inspecting plywood, comprising a step of determining that the composite single plate of the second and subsequent layers from the plywood surface is defective when a point indicating temperature is present on the straight line.