JPS6030307A - Manufacture of wooden plate - Google Patents

Abstract

PURPOSE:To produce the wooden plate keeping bending strength and screw holding strength, etc. constantly by a method in which the thickness change of the wooden plate at hot pressing is calculated and its specific gravity is measured, thereby correcting the weight of wooden small chip group, detecting the density of the wooden small chip group from said specific gravity. CONSTITUTION:The wooden small chip-group transferred to a heat pressing device 5 from a forming device 4 is press tightened under heating by a hot press 51. The thickness change at its displacement point is measured by a displacement indicator 52, and its measured value is inputted into an analyser 8. Then, the press operation signal at its displacement point is inputted also from the hot press 51 into the analyser 8. Next, after the value of the weight and surface of the wooden plate P transferred from the hot pressing device 5 has been inputted into the analyser 8, the specific gravity of the wooden plate P is calculated from each value thereof, thereby computing the density of the wooden small chip having the correlation therebetween. If this value deviates from a set value, a controlling signal is sent to the forming device 4 by way of the circuit C from the analyser 8, and the weight of the wooden small chip group scattered at the forming device 4 is controlled correspondingly to the density of the wooden small chip group. Thus, the wooden plate having the quality such as bending strength constantly may be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to (1) a method for manufacturing a wood board such as a particle board, and more specifically, the specific gravity of the wood board is measured by measuring the thickness of the wood board during hot pressing; This invention relates to a manufacturing method for manufacturing wood boards that maintain uniform physical performance such as bending strength and wood screw holding power by detecting the density of small pieces of wood that are raw materials that have a correlation with the above.

In wood boards manufactured by scattering and depositing small wood chips and pressing them under heat, the density of the wood chips, which are the raw material, determines the various properties of the finished wood board, such as bending strength and peel strength. In addition, it has a large effect on the holding power for wood screws, etc., and in order to maintain the various properties of these wood boards at a constant level, it is necessary to supply small pieces of wood at a predetermined density in advance.
The weight of the scattered wood particles must be adjusted to accommodate changes in the density of the wood particles.

However, in recent years, due to the depletion of wood resources, it has become impossible to use large quantities of small pieces of wood from the same tree species. For this reason, at present, small pieces of wood from different types of logs are often used in combination. If you use small pieces of wood from different types of logs like this.

Variations occur in the density of the entire group of wood particles, making it impossible to manufacture wood boards using a group of wood particles that always have a constant density. Moreover, it is difficult to measure the density of the wood particles each time during the manufacturing process.

Therefore, the various characteristics of the wood boards manufactured using the above-mentioned groups of wood chips vary each time and are not constant, and there are cases in which the quality is unreliable.

The present invention has been made to solve the above problems, and includes measuring changes in the thickness of a wooden board during hot pressing during the manufacturing process.
The specific gravity is measured from the thickness of the wood board corresponding to a certain heat-pressing time, and the density of a group of wood particles that has a correlation with this specific gravity is retrospectively detected, and if the detected density deviates from a predetermined range. In order to keep the bending strength and other physical properties of wood board products constant, we feed back this information and control the amount of wood particles that are scattered, thereby manufacturing wood boards that always maintain a constant bending strength and other quality. The purpose is to provide a method.

Hereinafter, the manufacturing method of the present invention will be explained in detail based on the drawings.

FIG. 1 is a schematic diagram showing the manufacturing process of a wooden board.

First, a raw material 1 consisting of raw wood is put into a small piece making machine 2 consisting of a flaker, a shaving machine, etc. In this small piece manufacturing machine 2, the shape of the small pieces is formed into a uniform size, such as a flake or a splinter, depending on the type of wood board to be manufactured and the raw material 1. The pieces produced by this piece production machine 2 are then subjected to a drying process so as to have a predetermined moisture content.

Next, the adhesive spraying device 3 sprays these small pieces with
Spray adhesive such as phenol resin.

Then, the small pieces are scattered and deposited in the tray of the molding device 4 to a predetermined thickness. In the case of forming a single-layer wood board, the material is spread and deposited using a belt conveyor or a vibrating spreader, and in the case of forming a multi-layer wood board, the surface layer and the inner layer are separately spread and deposited.

The board mat on which the wood particles have been scattered and deposited in this manner is heat-pressed by steaming in a heat-pressing device 5 in the next step. At this time, if the steaming pressure is kept constant, the pressing time and steaming temperature may need to be changed depending on the raw wood of the small piece or the type of adhesive. Further, the hot pressing by the hot pressing device 5 includes methods such as a so-called multi-stage hot press, a single-stage press, and a continuous press. The small wood pieces that have been subjected to heat and pressure by the heat and pressure device 5 form a certain shape as a wood board. And the final finishing process 6
After sanding and trimming, which involves cutting the wood to specified dimensions, the wood board is completed.
This is the so-called product 7.

FIG. 2 is an explanatory diagram for measuring the pressing time t and the displacement of the wood board thickness during hot pressing. That is, when compressing the board mat 11 with the steamers 12, 12 using the hydraulic pressure of the press 13,
A dynamic strain meter 15 measures the thickness displacement of the wood board via a displacement transducer 14 fixed to the steamer 12. Further, if necessary, the thickness displacement is recorded by the recording device 16.

As mentioned above, FIG. 3 shows the relationship between the thickness of the wood board measured during hot pressing and the pressing time t. In other words, during the time tl from the start of compaction to the displacement point A, the voids between the wooden pieces are compressed, but at this point A, about 35% of the voids in the wooden pieces themselves still remain, and the wooden board The specific gravity has not been compressed down to the density of the raw wood particles.

As the pressing time roughly elapses, the gaps between the wooden pieces are compressed and reduced from around point A, and the compression of the wooden pieces themselves and the compression of the gaps between the wooden pieces are performed at the same time. After the next displacement point B, the gaps between the small pieces of wood almost disappear, and only the small pieces of wood themselves are mainly compressed.

That is, if the thickness of the wood board is Ill at this time, the specific gravity G of the wood board is W/S from the predetermined area S crn' (approximately the bottom area of the tray) and the weight W (automatic weighing). It can be obtained as XIll.

Equation 1 can be obtained immediately by subtracting the thickness value J12 of the distance bar from the index bias of the measuring instrument. From these weighed and measured values, the density of small pieces of wood made of various types of raw materials,
When plotted with the so-called volumetric weight on the horizontal axis and the specific gravity G of the wood board manufactured from the wood chips on the vertical axis, the density of the wood chips and the specific gravity G of the wood board have a certain proportional relationship. This proportional relationship is expressed as y=ax+b.

That is, in the hot pressing process, the wood board thickness i for the pressing time tl
When t is smaller or larger than a predetermined thickness, the specific gravity Gl of the wood board is immediately measured by plowing the wood board 1. Then, by applying this G1 to the correlation equation obtained from FIG. 4, the density Q of the wood particles can be detected.

As a method for specifying the specific constant of the above correlation equation y=ax+b, the case of lauan material will be explained. First, the density of a small piece of lauan material is measured in advance. That is,
This density is 0.35 g/Cm'' and the area of the wood board (
The bottom area of the tray is 30cm in length and width, i.e. 900cm.
m', the weight of the wooden board is 804g, and the displacement point A
The thickness of the wooden board is 4.15 cm.

Then, using the formula for calculating the specific gravity G of the wood board, the specific gravity of the lauan wood board becomes 0.242 g/cm'.

In this way, the density of small pieces and specific gravity of wood boards of various raw materials such as paulownia, cedar, hemlock, and mahogany were measured, and the results are listed in Table 1 below.

Table 1 The densities and specific gravity shown in this list are plotted in the same way as in Figure 4, and a = 0.334. b = 0.1
18 and find the correlation formula, Y = 0.334 X
+0.118. That is, if the correlation formula is prepared in advance, and the specific gravity G of the wood board, so-called y value, is determined as described above, the density of the wood piece can be calculated.

As mentioned above, the density of the wood particles is immediately calculated from the value of the wood plank 1 and others, and if the value deviates from a certain range, it is fed back to the wood board manufacturing process and the weight of the wood particles to be scattered and deposited is calculated. By adjusting this, it is possible to manufacture a wood board with a certain bending strength.

Furthermore, the target bending strength, for example 200Kg/crn
If we show the relationship between wood particle density and wood particle group weight in order to obtain ' and 150Kg/ctn', we can obtain a relational expression as shown in the graph of Figure 5, so we can feed back this relational expression in the same way. By inputting these parameters, wood boards with the desired bending strength and other qualities can be manufactured.

Figure 5 shows an example of an actual press.
The group of small wood pieces conveyed from the molding device 4 to the thermopressing device 5 is
It is thermally compacted by a hot press 51, and the thickness displacement at the displacement point A at that time is measured by a displacement meter 52, and the value is input into an analysis device 8 consisting of a computer or the like. A press operation signal at point A is also input from the hot press 51 to the analysis device 8. Then, if the weight and area values of the wood board P taken out from the thermopressure device 5 are input into the analysis device 8, the specific gravity of the wood board at point A can be immediately calculated in this analysis device 8 from each input value. Then, the density of the wood particles is calculated using a correlation formula between the density of the wood particles and the specific gravity of the wood board. Moreover, if this value deviates from the preset density range,
In order to keep the bending strength and other quality constant, a control signal is sent from the analysis device 8 to the forming device 4 via the circuit C, and the weight of the wood particles scattered by the forming device 4 is determined by the wood particle density (
It increases or decreases depending on the volumetric weight). The range of increase/decrease is determined by inputting the relational expression shown in FIG. 5 into the analysis device 8 in advance, and determining the range of variation in volumetric weight.

As described above, the method for producing a wood board according to the present invention adjusts the weight of the wood chips according to the density of the wood chips, which has the greatest influence on the quality and performance of the wood board, so that the wood board always has stable performance quality. can be manufactured.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the process of manufacturing a wood board, Figure 2 is an explanatory diagram of a device that measures the relationship between the pressing time and the displacement of the wood board's thickness in the heat pressing process, and Figure 3 Figure 4 is a graph showing the relationship between compaction time and wood board thickness, and Figure 4 is a graph showing the correlation between the density of small pieces of wood and the specific gravity of the wood board. Figure 5 is a graph showing the relationship between the density (volume weight) of small wood pieces and the specific gravity of the board to be set when obtaining a wood board with the target bending strength. Figure 6 is the density of small wood pieces in an actual press. 1 is a schematic diagram of an apparatus for detecting. 4... Molding device, 5... Heat pressure device. 14... Displacement transducer, 15... Dynamic strain meter. Applicant Sanyo Kokusaku Valve Co., Ltd. Agent Patent attorney Kuninori Funabashi 1 Procedural amendment dated December 14, 1981 1, Indication of the case Patent application No. 137008/1982 2, Title of invention Method for manufacturing wood board 3, Amendment Patent applicant: Sanyo Kokusaku Pulp Co., Ltd. 4, agent address: 3-9-3 Nishi-Shinjuku, Shinjuku-ku, Tokyo 180 Voluntary amendment 6, detailed description of the invention in the specification subject to amendment Column: Brief description of the drawing Column: Drawing 3, Figure 7, Contents of amendment (1) "Thickness of wood board" on page 5, lines 15 to 18 of the specification was corrected to "Thickness of wood board L" do. (2) On page 6 of the specification, lines 12 and 13, [Method 1 can be obtained immediately by subtracting the thickness bias 2 of the distance bar from the indicator bias of the measuring instrument. ” is corrected as follows. [But 1 is the thickness of the distance bar, and if Sentence 2 is set to 0, the thickness value fL2 of the discun spar is determined by the index bias of the measuring instrument.
You can get it immediately by adding . ” (3) “Albezia 45%” on page 8, table 1, line 15 of the specification
” is corrected to “Albizia 45%”. (4) "Figure 5" on page 9, line 11 of the specification has been changed to "Figure 6"
and correct it. (5) In the specification, page 10, line 20, "of the heat pressure process" is corrected to "in the heat pressure process." (6) Correct Figure 3 as shown in the attached sheet.

Claims (1)

[Claims] 1. In the method of manufacturing a wood board by scattering and depositing a group of small pieces of wood to form a certain shape and then heat-pressing the wood, the change in the thickness of the wood board during the heat-pressing is measured, and the specific gravity of the wood board is calculated from the thickness. A method for producing a wood board, characterized in that the weight of the wood particles group, which is preset, is corrected by measuring the specific gravity and detecting the density of the wood particles group based on the specific gravity.