A method of producing a kerf plate core

Abstract

The present application relates to the technical field of wood-based board, and particularly relates to a production method of a cutout plate core, which forms a plurality of equidistant cut joints by cutting one side of the convex growth wheel of a chord cut plate, provides expansion joints for the chord direction with the largest free shrinkage deformation, releases local stress, and reduces the overall deformation of the chord cut plate in the chord direction. The method forms cut joints by cutting the middle of one side of the convex growth wheel of a half-chord half-radius plate, so that the texture angles of the half-chord half-radius plate on both sides of the cut are approximately 45 degrees, thereby reducing the difference in deformation in the width direction and the thickness direction and reducing local stress. The wood-based board formed by pasting and combining the chord cut plate and the half-chord half-radius plate after cutting can greatly inhibit the deformation of the wood-based board under the condition of environmental humidity change and improve the dimensional stability of the wood-based board.

Description

Technical Field

[0001] This invention relates to the field of plywood technology, and more particularly to a method for producing cut core boards. Background Technology

[0002] The core of plywood is typically made of small strips of wood, primarily sourced from fast-growing small-diameter timber and wood processing residues, specifically the core wood remaining after rotary veneer cutting. Based on grain angle, these core strips can be categorized into three types. Currently, factories typically dry these three types of core strips, then blend them into a core before processing it into plywood. However, changes in environmental humidity can cause problems. For example, plywood produced in humid southern regions may be sold in drier northern regions, and vice versa. Changes in the core's moisture content trigger free expansion and contraction. Due to differences in grain patterns across width and thickness among the different types of core strips, this further exacerbates the unevenness of the expansion and contraction, easily generating localized stress. This can lead to changes in the board's size and shape, affecting product usability. Therefore, developing a core material with high stability and resistance to both dryness and humidity is urgently needed. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for producing cut-out core boards, which solves the technical problem that existing plywood is prone to deformation under conditions of varying moisture content.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0007] A method for producing a cut-out core board includes the following steps:

[0008] A tangential cutting plate and a half-chord radius plate are provided. The tangential cutting plate and the half-chord radius plate have a first surface with a growth ring protrusion. Cuts are made on the first surface at a preset interval to form a plurality of cuts perpendicular to the first surface. The cuts are non-through cuts.

[0009] The chord-cut plate and the half-chord radius plate are initially planed, the first surface with the cut is placed on the same side, and the sides of the chord-cut plate and the half-chord radius plate perpendicular to the first surface are glued together to form a cut plate core.

[0010] When making a cut on the first surface of the tangential cutting plate, a cut is made every 1 / 3 of the width of the first surface, and the width of the cut is 1-2 mm, and the depth of the cut is 1 / 2 of the thickness of the tangential cutting plate.

[0011] When making a cut on the first surface of the half-chord radius plate, the cut is made along the centerline in the width direction of the first surface, and the width of the cut is 1-2 mm, and the depth of the cut is 1 / 2 of the thickness of the half-chord radius plate.

[0012] The texture angle of the half-chord radius plates on both sides of the cut is 45°.

[0013] The tangential cut board and the half-tangential radius board are obtained by sawing and drying small-diameter logs with a diameter of 13-14cm; the small-diameter logs include two tree species: fir and poplar.

[0014] The tangential cut board and the half-tangential radius board are obtained by sawing and drying a wood core with a radius of 10-14cm; the wood core is the wood core remaining after the log is rotary-cut into veneers.

[0015] It also includes: applying glue to the first surface and the opposite surface of the cut core and covering them with 3mm thick eucalyptus veneer, then hot-pressing them into plywood.

[0016] Each of the cut core plates has a width of 50-60mm and a thickness of 30mm.

[0017] The tangential cutting plate is a core strip with a texture angle α between the growth ring tangent and the wide side of the core strip being 0 ≤ α < 45°;

[0018] The semi-chord radius plate is a core strip with a texture angle α of 45°≤α<90° between the tangent of the growth ring and the wide side of the core strip.

[0019] A type of plywood is produced using the above-described production method.

[0020] (III) Beneficial Effects

[0021] The beneficial effects of the present invention are as follows: The present invention provides a method for producing a cut-out core plate. By making a cut on one side of the growth wheel protrusion of the tangential cut plate, a number of equally spaced cuts are formed, which provides an expansion joint for the tangential direction with the greatest degree of free expansion and contraction deformation, releases local stress, and reduces the overall deformation of the tangential cut plate in the tangential direction.

[0022] By making a cut in the middle of one side of the protrusion of the half-chord radius plate growth wheel, a slit is formed, so that the texture angle of the half-chord radius plate on both sides of the cut is approximately 45°, thereby reducing the differential deformation in the width and thickness directions and reducing local stress.

[0023] By gluing together tangentially cut boards and semi-tangentially cut boards to form a plywood, the deformation of the plywood under varying environmental humidity conditions can be significantly suppressed, thus improving the dimensional stability of the plywood. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the slit in the tangential cutting plate of the present invention;

[0025] Figure 2 This is a schematic diagram of the slit cut of the semi-chord radius plate of the present invention.

[0026] [Explanation of Labels in the Attached Image]

[0027] 1: tangential plate;

[0028] 2: Half-chord radius plate;

[0029] 3: Cutting the seam. Detailed Implementation

[0030] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0032] The following will provide specific definitions for the terms used in this article.

[0033] The term "core strip" is defined as a sawn strip with a rectangular cross-section, obtained by sawing a log parallel to its axial direction, and the grain on the rectangular cross-section being the growth ring grain of the log. The core strip includes: tangential plate 1, semi-tangential radius plate 2, and radial plate.

[0034] The term "texture angle" as used herein is defined as the angle between the tangent of the growth ring and the broad side of the core strip. The term "tangential plate 1" is defined as a core strip where the texture angle α between the tangent of the growth ring and the broad side of the core strip is 0 ≤ α < 45°. The term "semi-chord radius plate 2" is defined as a core strip where the texture angle α between the tangent of the growth ring and the broad side of the core strip is 45° ≤ α < 90°. The term "radial plate" is defined as a core strip where the texture angle α between the tangent of the growth ring and the broad side of the core strip is 90°.

[0035] Regarding the terms "consistent growth ring orientation" and "substantially parallel" and similar terms, it should be noted that timber is a natural product, and the morphology of trees varies significantly as they grow. This means that the growth rings at the center of the tree are off-center from the outer edges, or that local variations occur around knots. This will result in some variation in the arrangement of growth rings on the end face of a single sawn board, but on average, the growth ring orientation remains consistent. Overall and geometric references should represent the basic invention and indicate that the selected center or radius may shift or vary during the sawing operation. These variations occur when sawing logs across the diameter, with the selected effective center intentionally or unintentionally changing from one half to the other and becoming different points, so that sawing can be performed parallel to or close to the center or radius.

[0036] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0037] This invention provides a method for producing a cut-out core plate, comprising the following steps:

[0038] Step 1: Classify the small-diameter logs used to make core strips, mainly including two tree species: cedar and poplar.

[0039] Step 2: The logs are sawn to obtain core strips with three different grain angles. The core strips include: tangential veneer 1, semi-tangential radius veneer 2, and radial veneer. In this embodiment, tangential veneer 1 and semi-tangential radius veneer 2 are obtained by sawing small-diameter logs with a diameter of 13-14cm and then drying them conventionally; or tangential veneer 1 and semi-tangential radius veneer 2 are obtained by sawing wood cores with a radius of 10-14cm and then drying them conventionally. The wood core is the wood core remaining after veneer rotary cutting of the logs.

[0040] In this embodiment, each core strip has a width of 50-60mm and a thickness of 30mm.

[0041] Regarding the selection of thickness, in practical applications, core strips that are too thin require multiple gluing and splicing during reassembly to achieve the preset dimensions. Multiple gluing and splicing will affect the quality of the plywood.

[0042] Among them, the tangential plate 1 has an angle of 0-45° between the tangent of the growth ring and the wide side of the core strip; the semi-chordal plate 2 has an angle of 45-90° between the tangent of the growth ring and the wide side of the core strip; and the radial plate has an angle of 90° between the tangent of the growth ring and the wide side of the core strip.

[0043] Step 3: Select the core strips of the chord-cutting plate 1 and the half-chord radius plate 2.

[0044] The upper surface of the tangential cutting plate 1 (the side with the protrusion of the growth ring) is slit, i.e., slits are made at equal intervals along the width direction of the tangential cutting plate 1. In this embodiment, a slit is made at every third point along the width direction of the tangential cutting plate 1. The width of the slit 3 is 1-2 mm, and the depth of the slit 3 is 1 / 2 of the thickness. In this embodiment, the thickness is approximately 6 mm. This provides an expansion joint in the tangential direction where the free expansion and contraction deformation is greatest, releasing local stress and reducing the overall deformation of the tangential cutting plate 1 in the tangential direction.

[0045] Since the convex surface experiences the greatest deformation, the side with the convex growth ring is chosen for the incision. The width direction of the tangential cut plate 1 refers to the direction of the long side of the tangential cut plate 1 after the log is cut into it.

[0046] The upper surface of the semi-chord radius plate 2 (the side with the protrusion of the growth ring) is cut, specifically, a cut is made at the midline of the width of the semi-chord radius plate 2. The width of the cut 3 is 1-2 mm, and the depth of the cut 3 is half the thickness. In this embodiment, the thickness is approximately 6 mm, so that the texture angle of the semi-chord radius plate 2 on both sides of the cut is approximately 45°. The texture angle is the angle between the tangent of the growth ring and the wide side of the core strip. This reduces the differential deformation in the width and thickness directions, and decreases local stress.

[0047] Step 4: After initial planing, glue the tangential cut plate 1 and the half-chord radius plate 2 together, and then attach them to the narrow side, that is, glue the sides of the tangential cut plate 1 and the half-chord radius plate 2 together to form the core from the side. The two types of core strips can be mixed and matched randomly, but the cut surfaces must be placed on the same side when splicing the boards.

[0048] Step 5: Finally, cover the top and bottom surfaces of the core board with 3mm thick eucalyptus veneer and then glue and press to form a plywood.

[0049] Since wood is an anisotropic material, its tangential moisture absorption deformation is about 1.5-2 times that of the radial deformation. Therefore, in order to avoid excessive tangential material being concentrated in the width or thickness direction of the board, the above-mentioned production method is used to cut the tangential board 1 and the half-tangential radius board 2, which can effectively suppress the deformation of the plywood in a humid environment.

[0050] This invention provides a method for producing a cut-out core plate. By making a cut on one side of the growth wheel protrusion of the tangential cut plate 1, a number of equally spaced cuts 3 are formed, which provide expansion joints for the tangential direction with the greatest degree of free expansion and contraction deformation, release local stress, and reduce the overall deformation of the tangential cut plate 1 in the tangential direction.

[0051] By making a cut in the middle of one side of the growth wheel protrusion of the half-chord radius plate 2, a slit 3 is formed, so that the texture angle of the half-chord radius plate 2 on both sides of the cut is approximately 45°, thereby reducing the differential deformation in the width and thickness directions and reducing local stress.

[0052] By gluing together the tangentially cut board 1 and the semi-tangential radius board 2 to form a plywood, the deformation of the plywood under varying environmental humidity conditions can be suppressed to a large extent, thus improving the dimensional stability of the plywood.

[0053] Based on the above-mentioned cut-core board production method, the following two sets of test data are provided to compare untreated blockboard with blockboard produced by the cut-core board production method. This demonstrates that blockboard produced by the cut-core board production method is less prone to deformation.

[0054] Example 1:

[0055] Test conditions: First, two types of plywood samples, one with an uncut core and the other with a cut core, were placed in a constant temperature and humidity chamber at 20℃ and 65% relative humidity. When the difference in mass between two weighings 24 hours apart did not exceed 0.1% of the previous sample mass, the mass was considered constant. The longitudinal, transverse, and thickness dimensions of the samples were then measured. Next, the two types of samples were placed in a constant temperature and humidity chamber at 20℃ and 30% relative humidity. When the difference in mass between two weighings 24 hours apart did not exceed 0.1% of the previous sample mass, the mass was considered constant. The longitudinal, transverse, and thickness dimensions of the samples were measured again. Finally, the shrinkage rate of the plywood was calculated using the following formula:

[0056]

[0057] In the formula:

[0058] SH—The shrinkage rate of the sample in the longitudinal (transverse and thickness directions), %, when the temperature is 20℃ and the relative humidity decreases from 65% to 30%.

[0059] S 65L (S 65T S 65H — The longitudinal (transverse and thickness) dimension of the sample when it reaches constant mass under conditions of 20℃ and 65% relative humidity, in millimeters (mm);

[0060] S 30L (S 30T S 30H — The longitudinal (transverse and thickness) dimension of the sample when it reaches constant mass under conditions of 20℃ and 30% relative humidity, in millimeters (mm).

[0061] The following table compares the shrinkage rates of plywood produced in the current factory conditions (i.e., uncut core boards) and plywood made with cut core boards:

[0062]

[0063] Based on the above experimental data, it can be concluded that the tests on the cores of Chinese fir and poplar showed that cutting the core of the tangentially cut plywood can significantly inhibit the shrinkage deformation of the plywood in the longitudinal, transverse and thickness directions in a dry environment. Especially in the thickness direction where the deformation is the greatest, the shrinkage deformation inhibition effect is improved by about 50% after the "cutting" treatment.

[0064] Example 2:

[0065] Test conditions: First, two types of plywood samples, one with an uncut core and the other with a cut core, were placed in a constant temperature and humidity chamber at 20℃ and 65% relative humidity. The mass was considered constant when the difference between two weighings 24 hours apart did not exceed 0.1% of the previous sample's mass. The longitudinal, transverse, and thickness dimensions of the samples were then measured. Next, the two types of samples were placed in a constant temperature and humidity chamber at 40℃ and 90% relative humidity. The mass was considered constant again when the difference between two weighings 24 hours apart did not exceed 0.1% of the previous sample's mass. The longitudinal, transverse, and thickness dimensions of the samples were measured again. Finally, the moisture expansion rate of the plywood was calculated using the following formula:

[0066]

[0067] In the formula:

[0068] SW—The rate of moisture expansion of the sample in the longitudinal (transverse and thickness directions), %, when the temperature and relative humidity increase from 20℃ and 65% to 40℃ and 90%, respectively.

[0069] S 65L (S 65T S 65H — The longitudinal (transverse and thickness) dimension of the sample when it reaches constant mass under conditions of 20℃ and 65% relative humidity, in millimeters (mm);

[0070] S 90L (S 90T S 90H — The longitudinal (transverse and thickness) dimension of the sample when it reaches constant mass under conditions of 40℃ and 90% relative humidity, in millimeters (mm).

[0071] The following table compares the moisture swelling rates of plywood produced in the current factory conditions (i.e., uncut core boards) and plywood made with cut core boards:

[0072]

[0073] Based on the above experimental data, it can be concluded that the tests on the cores of the two tree species, Chinese fir and poplar, show that cutting the core of the tangentially cut board can significantly inhibit the swelling and deformation of the plywood in the longitudinal, transverse and thickness directions in a humid environment. Especially in the thickness direction where the deformation is the greatest, the effect of inhibiting swelling and deformation is improved by about 50% after the "cutting" treatment.

[0074] In summary, the most critical reason why plywood is prone to warping and deformation in application is the large deformation in the thickness direction under dry and wet environments. Plywood produced by the cut-core production method has achieved a deformation suppression effect of about 50% in the thickness direction.

[0075] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0076] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0077] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," or "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0078] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0079] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for producing a cut-out core board, characterized in that, Includes the following steps: The logs are sawn to obtain core strips with three different grain angles. The core strips include: tangential cut plate (1), half-tangential radius plate (2), and radial cut plate. Select a chord-cutting plate (1) and a half-chord radius plate (2). The chord-cutting plate (1) and the half-chord radius plate (2) have a first surface with a growth ring protrusion. Cuts are made on the first surface at a preset interval to form a number of cuts (3) perpendicular to the first surface. The cuts are non-through cuts. The width of the cuts (3) is 1-2 mm and the depth is 1 / 2 of the thickness of the chord-cutting plate (1) or the half-chord radius plate (2). When making a cut on the first surface of the tangential cutting plate (1), a cut is made every 1 / 3 of the width of the first surface. When the first surface of the half-chord radius plate (2) is cut, the cut is made along the centerline in the width direction of the first surface so that the texture angle of the half-chord radius plate (2) on both sides of the cut (3) is 45°. After cutting the chord plate (1) and the half-chord radius plate (2), a preliminary planing is performed, the first surface with the cut (3) is placed on the same side, and the sides of the chord plate (1) and the half-chord radius plate (2) perpendicular to the first surface are glued together to form a cut plate core.

2. The method for producing a cut-out core according to claim 1, characterized in that, The tangential cutting board (1) and the half-tangential radius board (2) are obtained by sawing and drying small-diameter logs with a diameter of 13-14cm; the small-diameter logs include two tree species: fir and poplar.

3. The method for producing a cut-out core according to claim 1, characterized in that, The tangential cut board (1) and the half-tangential radius board (2) are obtained by sawing and drying a wood core with a radius of 10-14cm; the wood core is the wood core remaining after the log is veneered and rotary cut.

4. The method for producing a cut-out core according to claim 1, characterized in that, Also includes: After applying glue to the first surface and the opposite surface of the cut core and covering it with a 3mm thick eucalyptus veneer, the boards are hot-pressed to form a plywood.

5. The method for producing a cut-out core according to claim 1, characterized in that, Each of the cut-out core strips has a width of 50-60mm and a thickness of 30mm.

6. The method for producing a cut-out core according to claim 5, characterized in that, The tangential cutting plate (1) is a core strip with a texture angle α between the growth ring tangent and the wide side of the core strip being 0 ≤ α < 45°; The semi-chord radius plate (2) is a core strip with a texture angle α of 45°≤α<90° between the tangent of the growth ring and the wide side of the core strip.

7. A type of plywood, characterized in that, It is produced by the production method described in any one of claims 1-6.

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