Large-size bamboo board pressing process

Abstract

The invention provides a large-size bamboo board pressing process which aims at optimizing the mechanical structure of a bamboo board, reducing transverse stress and improving the bending resistance and the pressure resistance of the bamboo board in large-size application. The technology comprises the steps that the two ends of a bamboo board are precisely machined to form multiple structures of the first shape, the second shape and the third shape so as to ensure tight matching of the splicing positions and optimization of the mechanical property; the surface of the bamboo board is polished, and an isocyanate adhesive is coated to serve as an adhesive, so that the high temperature resistance and the bonding strength are enhanced; through a criss-cross multi-layer stacking mode, the bending resistance and the compression resistance of the bamboo board are improved; a multi-stage hot-pressing process is adopted, uniform heating of the bamboo board is ensured, and stress concentration caused by local temperature difference is avoided. The method is suitable for bamboo board material processing in the fields of buildings, furniture and the like, and the strength and stability of large-size bamboo boards are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the field of bamboo board processing, discloses a large-size bamboo board pressing process, and particularly relates to a processing technology for processing and preparing large-size and wide bamboo boards. Background Art

[0002] As a natural, environmentally friendly and renewable resource, bamboo has a wide range of applications in many fields such as construction, furniture, and decoration. In particular, it has gradually become an important material choice in modern green buildings and environmentally friendly products. Bamboo has the advantages of light weight, high strength, and good durability. Compared with wood, bamboo has a short growth cycle and low carbon emissions. Therefore, in the context of sustainable development, the market demand for bamboo continues to grow. However, with the increasing market demand for large-size bamboo boards, traditional bamboo board processing technology has exposed many technical bottlenecks in large-size application scenarios, especially in terms of mechanical properties, compressive strength, bending resistance and durability.

[0003] First, the traditional bamboo board splicing method usually relies on plane splicing technology. This splicing technology is relatively simple, but in large-sized bamboo board materials, the splicing points often become the weak link in mechanical properties, resulting in stress concentration at the splicing points when subjected to force. Especially under the action of lateral stress, the bamboo board is prone to cracking, warping or deformation, reducing its bending and compression resistance. Secondly, there are also problems with the selection and application of adhesives in the traditional lamination process. Commonly used adhesives have limited high temperature resistance. With the passage of time or in high temperature environments, the adhesive layer is prone to aging and degumming, affecting the durability and strength of the bamboo board.

[0004] In addition, the existing hot pressing process lacks precision in controlling temperature and pressure. Especially in the production of large-sized bamboo boards, uneven heating often leads to excessive local temperature differences in the bamboo boards, which in turn causes uneven stress distribution within the boards. This deficiency in hot pressing further leads to inconsistent mechanical properties of bamboo boards in practical applications, especially in high-load application scenarios, where the structural stability of bamboo boards cannot be effectively guaranteed.

[0005] At present, in order to meet the actual application needs of large-sized bamboo boards, it is urgent to improve and optimize the traditional bamboo board pressing process, especially to innovate and break through in bamboo board structure design, adhesive selection and hot pressing process control. By precisely processing the shapes of both ends of the bamboo board and using optimized splicing methods, the structural stability of the splicing can be greatly improved, and the influence of lateral stress on the overall strength of the bamboo board can be reduced. Summary of the invention

[0006] The purpose of the present invention is to develop a lamination process capable of preparing large-sized and wide bamboo boards to meet the demand for large-area bamboo boards in application scenarios such as construction, furniture, and decoration. Through innovative processing, splicing, and lamination technologies, the present invention can effectively improve the structural strength of large-scale bamboo boards, especially maintaining the overall stability and durability of the boards when the width increases.

[0007] Specifically, the invention can significantly increase the width of the bamboo board without sacrificing material properties, while reducing the impact of lateral stress by designing edge processing of the bamboo board in multiple shapes, using an efficient adhesive formula and an optimized hot pressing process. This innovative process can not only solve the problem of reduced bending and compression resistance caused by increased width of the bamboo board in traditional processes, but also significantly improve the service life and load-bearing performance of large-size bamboo boards in applications, meeting the high-strength requirements of large-format bamboo board materials.

[0008] In order to achieve the purpose of the invention, the technical solution adopted by the present invention is: a large-size bamboo board pressing process, the large-size bamboo board pressing process comprises the following steps:

[0009] S1 first processes the two ends of the bamboo board into multiple shapes, forming shapes one, two, and three respectively; each shape is precisely calculated and cut to ensure a tight fit and optimized strength when finally spliced;

[0010] Before S2 splices, the surface of the bamboo board is polished to ensure a smooth and flawless surface, and adhesive is precisely applied to improve strength and high temperature resistance; on this basis, the curvature of adjacent bamboo boards is precisely matched to ensure seamless splicing and uniform penetration of adhesive;

[0011] S3 stacks the treated bamboo boards in multiple layers in a crisscross order, with each layer of bamboo boards arranged at a 90-degree angle to the previous layer to maximize the overall bending and compression resistance and ensure that the adhesive between each layer is in full contact;

[0012] S4 is initially pressed at 60-70℃ and 1-1.2MPa for 5-8 minutes, and then the temperature is increased to 125-140℃ and the pressure is 10-14MPa for 18-30 minutes to fully cure the adhesive. The heating should be gradually heated in different areas to ensure that the bamboo board is heated evenly and to prevent the local temperature from being too high or too low.

[0013] After S5 is completed with hot pressing, the bamboo board is cooled for 5 to 10 minutes, and the pressure is maintained at 4 to 6 MPa to maintain the shape of the board during the cooling process. Then, it is sanded to ensure a smooth surface and remove excess glue.

[0014] S6 passes multiple tests such as thickness, flatness, and strength to ensure that the finished bamboo panels meet the quality standards for large-size applications.

[0015] According to a large-size bamboo panel lamination process, the shape one described in S1 is a horizontal line at the top, forming a right-angled depression downward, extending into a sharp inverted V-shaped groove, forming a right-angled protrusion again, and ending with a short horizontal line to facilitate interlocking with adjacent structures.

[0016] According to a large-size bamboo board pressing process, the shape 2 described in S1 is a short horizontal line at the top, followed by two right-angle depressions formed downward to form a stepped notch structure.

[0017] According to a large-size bamboo board pressing process, the shape three described in S1 is an inclined "S" shape at the interface, which is first convex and then concave and gradually moves downward.

[0018] According to a large-size bamboo board lamination process, the adhesive described in S2 is isocyanate glue.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) Ability to prepare large-size bamboo boards: The core of the present invention is that it can effectively prepare wide and large-size bamboo boards. Through precise edge processing design and splicing process, the joints are tightly fitted, so that the overall strength of the structure is maintained when the width is increased. Compared with the traditional bamboo board pressing process, the bamboo board with expanded width has better bending and compression resistance, and is suitable for large-area applications, such as flooring, wall decoration and other fields.

[0021] (2) Optimizing transverse stress: Wide bamboo boards are prone to cracking or deformation under transverse stress, but the present invention greatly reduces the problem of transverse stress concentration through optimized structural design. Especially at the joints, through the design of multiple shapes and staggered stacking process, the transverse stress is dispersed to avoid bending or cracking of large-sized bamboo boards, ensuring the structural stability of the board after the width is expanded.

[0022] (3) Enhanced bonding strength: The use of isocyanate adhesive has excellent high temperature resistance and strength, ensuring that the bonding performance of bamboo boards is long-lasting and reliable under high load and high temperature environments.

[0023] (4) Enhanced durability: Through scientific process steps, the durability of bamboo boards is improved, aging and degumming during long-term use are reduced, and the service life of the product is increased.

[0024] (5) Environmental protection characteristics: Bamboo itself has the characteristics of being renewable and environmentally friendly. Combined with the process of the present invention, it further promotes the concept of sustainable development and conforms to the trend of modern green buildings and environmentally friendly products.

[0025] Instruction Manual

[0026] Figure 1 The interface structure processed in embodiments 1 and 2;

[0027] Figure 2 The interface structure processed in the third and fourth embodiments;

[0028] Figure 3 The interface structure processed in Embodiments 5 and 6; DETAILED DESCRIPTION

[0029] Embodiment 1

[0030] First, the two ends of the bamboo board are processed to form a shape, such as Figure 1 As shown. Before splicing, the surface of the bamboo board is polished to ensure that the surface is smooth and flawless, and the adhesive is accurately applied to improve the strength and high temperature resistance; on this basis, the adjacent bamboo boards are precisely matched in arc to ensure seamless splicing and uniform penetration of the adhesive. The treated bamboo boards are stacked in multiple layers in a criss-cross order, and the arrangement direction of each layer of bamboo boards is at a 90-degree angle to the previous layer to maximize the overall bending and compression resistance, and ensure that the adhesive between each layer is fully in contact. Initially press at 60℃ and 1MPa for 6 minutes, then increase the temperature to 138℃ and the pressure to 14MPa for 18 minutes to fully cure the adhesive. The heating should be gradually heated in different areas to ensure that the bamboo board is heated evenly and prevent the local temperature from being too high or too low. After the hot pressing is completed, the bamboo board is cooled for 6 minutes, and the pressure is maintained at 4MPa to maintain the stability of the board shape during the cooling process. Then sanding is performed to ensure that the surface is flat and remove excess glue. Use a dedicated thickness gauge to perform multi-point measurements at different locations (edges and centers) on the bamboo board to ensure that the thickness of the bamboo board is consistent and the tolerance is within the specified range. Use a combination of a ruler and a feeler gauge to test the overall flatness of the bamboo board, especially the flatness of the joints, to ensure that there are no obvious bumps or warps to meet the high standards of building or furniture materials. Once the requirements are met, the desired product is obtained.

[0031] Embodiment 2

[0032] First, the two ends of the bamboo board are processed to form a shape, such as Figure 1As shown. Before splicing, the surface of the bamboo board is polished to ensure that the surface is smooth and flawless, and the adhesive is accurately applied to improve the strength and high temperature resistance; on this basis, the adjacent bamboo boards are precisely matched in arc to ensure seamless splicing and uniform penetration of the adhesive. The treated bamboo boards are stacked in multiple layers in a criss-cross order, and the arrangement direction of each layer of bamboo boards is at a 90-degree angle to the previous layer to maximize the overall bending and compression resistance, and ensure that the adhesive between each layer is fully in contact. Initially press at 70℃ and 1.2MPa for 8 minutes, then increase the temperature to 140℃ and the pressure to 14MPa for 18 minutes to fully cure the adhesive. The heating should be gradually heated in different areas to ensure that the bamboo board is heated evenly and prevent the local temperature from being too high or too low. After the hot pressing is completed, the bamboo board is cooled for 30 minutes, and the pressure is maintained at 6MPa to maintain the stability of the board shape during the cooling process. Then sanding is performed to ensure that the surface is flat and remove excess glue. Use a dedicated thickness gauge to perform multi-point measurements at different locations (edges and centers) on the bamboo board to ensure that the thickness of the bamboo board is consistent and the tolerance is within the specified range. Use a combination of a ruler and a feeler gauge to test the overall flatness of the bamboo board, especially the flatness of the joints, to ensure that there are no obvious bumps or warps to meet the high standards of building or furniture materials. Once the requirements are met, the desired product is obtained.

[0033] Embodiment 3

[0034] First, the two ends of the bamboo board are processed to form shape 2, such as Figure 2 As shown. Before splicing, the surface of the bamboo board is polished to ensure that the surface is smooth and flawless, and the adhesive is accurately applied to improve the strength and high temperature resistance; on this basis, the adjacent bamboo boards are precisely matched in arc to ensure seamless splicing and uniform penetration of the adhesive. The treated bamboo boards are stacked in multiple layers in a criss-cross order, and the arrangement direction of each layer of bamboo boards is at a 90-degree angle to the previous layer to maximize the overall bending and compression resistance, and ensure that the adhesive between each layer is fully in contact. Initially press at 60℃ and 1MPa for 8 minutes, then increase the temperature to 138℃ and the pressure to 14MPa for 20 minutes to fully cure the adhesive. The heating should be gradually heated in different areas to ensure that the bamboo board is heated evenly and prevent the local temperature from being too high or too low. After the hot pressing is completed, the bamboo board is cooled for 15 minutes, and the pressure is maintained at 4MPa to maintain the stability of the board shape during the cooling process. Then sanding is performed to ensure that the surface is flat and remove excess glue. Use a dedicated thickness gauge to perform multi-point measurements at different locations (edges and centers) on the bamboo board to ensure that the thickness of the bamboo board is consistent and the tolerance is within the specified range. Use a combination of a ruler and a feeler gauge to test the overall flatness of the bamboo board, especially the flatness of the joints, to ensure that there are no obvious bumps or warps to meet the high standards of building or furniture materials. Once the requirements are met, the desired product is obtained.

[0035] Embodiment 4

[0036] First, process both ends of the bamboo board to form shape 2, such as Figure 2 As shown. Before splicing, the surface of the bamboo board is polished to ensure that the surface is smooth and flawless, and the adhesive is accurately applied to improve the strength and high temperature resistance; on this basis, the adjacent bamboo boards are precisely matched in arc to ensure seamless splicing and uniform penetration of the adhesive. The treated bamboo boards are stacked in multiple layers in a criss-cross order, and the arrangement direction of each layer of bamboo boards is at a 90-degree angle to the previous layer to maximize the overall bending and compression resistance, and ensure that the adhesive between each layer is fully in contact. Initially press at 70℃ and 1.2MPa for 10 minutes, then increase the temperature to 138℃ and the pressure to 14MPa for 20 minutes to fully cure the adhesive. The heating should be gradually heated in different areas to ensure that the bamboo board is heated evenly and prevent the local temperature from being too high or too low. After the hot pressing is completed, the bamboo board is cooled for 12 minutes, and the pressure is maintained at 6MPa to maintain the shape of the board during the cooling process. Then sanding is performed to ensure that the surface is flat and remove excess glue. Use a dedicated thickness gauge to perform multi-point measurements at different locations (edges and centers) on the bamboo board to ensure that the thickness of the bamboo board is consistent and the tolerance is within the specified range. Use a combination of a ruler and a feeler gauge to test the overall flatness of the bamboo board, especially the flatness of the joints, to ensure that there are no obvious bumps or warps to meet the high standards of building or furniture materials. Once the requirements are met, the desired product is obtained.

[0037] Embodiment 5

[0038] First, the two ends of the bamboo board are processed to form shape three, such as Figure 3As shown. Before splicing, the surface of the bamboo board is polished to ensure that the surface is smooth and flawless, and the adhesive is accurately applied to improve the strength and high temperature resistance; on this basis, the adjacent bamboo boards are precisely matched in arc to ensure seamless splicing and uniform penetration of the adhesive. The treated bamboo boards are stacked in multiple layers in a criss-cross order, and the arrangement direction of each layer of bamboo boards is 90 degrees to the previous layer to maximize the overall bending and compression resistance, and ensure that the adhesive between each layer is fully in contact. Initially press at 60℃ and 1MPa for 10 minutes, then increase the temperature to 140℃ and the pressure to 14MPa for 20 minutes to fully cure the adhesive. The heating should be gradually heated in different areas to ensure that the bamboo board is heated evenly and prevent the local temperature from being too high or too low. After the hot pressing is completed, the bamboo board is cooled for 15 minutes, and the pressure is maintained at 4MPa to maintain the stability of the board shape during the cooling process. Then sanding is performed to ensure that the surface is flat and remove excess glue. Use a dedicated thickness gauge to perform multi-point measurements at different locations (edges and centers) on the bamboo board to ensure that the thickness of the bamboo board is consistent and the tolerance is within the specified range. Use a combination of a ruler and a feeler gauge to test the overall flatness of the bamboo board, especially the flatness of the joints, to ensure that there are no obvious bumps or warps to meet the high standards of building or furniture materials. Once the requirements are met, the desired product is obtained.

[0039] Embodiment 6

[0040] First, the two ends of the bamboo board are processed to form shape three, such as Figure 3 As shown. Before splicing, the surface of the bamboo board is polished to ensure that the surface is smooth and flawless, and the adhesive is accurately applied to improve the strength and high temperature resistance; on this basis, the adjacent bamboo boards are precisely matched in arc to ensure seamless splicing and uniform penetration of the adhesive. The treated bamboo boards are stacked in multiple layers in a criss-cross order, and the arrangement direction of each layer of bamboo boards is at a 90-degree angle to the previous layer to maximize the overall bending and compression resistance, and ensure that the adhesive between each layer is fully in contact. Initially press at 70℃ and 1.2MPa for 5 minutes, then increase the temperature to 140℃ and the pressure to 15MPa for 20 minutes to fully cure the adhesive. The heating should be gradually heated in different areas to ensure that the bamboo board is heated evenly and prevent the local temperature from being too high or too low. After the hot pressing is completed, the bamboo board is cooled for 10 minutes, and the pressure is maintained at 6MPa to maintain the shape of the board during the cooling process. Then sanding is performed to ensure that the surface is flat and remove excess glue. Use a dedicated thickness gauge to perform multi-point measurements at different locations (edges and centers) on the bamboo board to ensure that the thickness of the bamboo board is consistent and the tolerance is within the specified range. Use a combination of a ruler and a feeler gauge to test the overall flatness of the bamboo board, especially the flatness of the joints, to ensure that there are no obvious bumps or warps to meet the high standards of building or furniture materials. Once the requirements are met, the desired product is obtained.

[0041] Embodiment 7

[0042] Purpose

[0043] In order to verify the bending and compression resistance of the large-size and wide-width bamboo board pressing process of the present invention, as well as the optimization effect on transverse stress, the following test process is designed, and the bending, compression and transverse stress tests are carried out according to the Chinese national standard (GB) to evaluate its mechanical properties.

[0044] Test samples

[0045] The test samples are the boards in Examples 1, 2, 3, 4, 5 and 6, and common commercially available bamboo boards, and the sample sizes are uniformly: width 1200 mm, length 2400 mm, and thickness 14 mm.

[0046] Bending performance test

[0047] Test standard: Conducted in accordance with the bending strength test in the Chinese national standard GB / T 17657-2013 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels".

[0048] Testing equipment: three-point bending tester.

[0049] Test steps:

[0050] S1 Place the sample on the three-point bending device, and set the support span to two-thirds of the sample length, i.e. 1600mm, according to the national standard requirements;

[0051] S2 applies a uniform vertical load in the center of the sample and gradually increases the load until the sample breaks;

[0052] S3 records the maximum load value and calculates the bending strength according to the formula: σ1=3FL / 2bh2 (where F is the maximum load, L is the support span, b and h are the width and thickness of the sample, respectively);

[0053] Compression performance test

[0054] Test standard: The compressive strength test is carried out according to the Chinese national standard GB / T 1936.1-2009 "Test method for compressive strength of wood parallel to the grain".

[0055] Testing equipment: Compression testing machine.

[0056] Test steps:

[0057] The size of the S1 cutting sample is 50mm×50mm×14mm;

[0058] S2 places the sample vertically on the compressor, applies a vertical load, and gradually increases the pressure until the sample is destroyed;

[0059] S3 records the maximum load and calculates the compressive strength according to the formula: σ2 = P / A (where P is the maximum load and A is the cross-sectional area of ​​the sample);

[0060] Transverse stress test

[0061] Test standard: According to the transverse tensile strength test specified in GB / T 17657-2013 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels".

[0062] Testing equipment: stress testing machine and strain gauge.

[0063] Test steps:

[0064] S1 fixes the strain gauge on the side of the sample and applies tension in the transverse direction, gradually increasing the load and recording the maximum tensile strength.

[0065] S2 uses a stress testing machine to measure the stress of transverse tension and evaluates it based on the transverse force conditions.

[0066] S3 Record the strain and stress values ​​of the sample and calculate the transverse stress. The transverse stress formula is: τ = F / A (where F is the applied transverse force and A is the force-bearing area);

[0067] Test conditions

[0068] The temperature was controlled at 20℃±2℃ and the humidity was controlled at 65%±5% in a laboratory environment. Each group of samples was tested three times to ensure the reliability of the data.

[0069] Test Results

[0070]

[0071] Conclusion: Through the above data, it can be clearly verified that the large-size bamboo board pressing process of the present invention is superior in mechanical properties and is suitable for application scenarios requiring high strength and high stability.

Claims

1. A large-size bamboo board pressing process, It is characterized in that The large-size bamboo board pressing process comprises the following steps: S1 first processes the two ends of the bamboo board into multiple shapes, forming shapes one, two, and three respectively; each shape is precisely calculated and cut to ensure a tight fit and optimized strength when finally spliced; Before S2 splices, the surface of the bamboo board is polished to ensure a smooth and flawless surface, and adhesive is precisely applied to improve strength and high temperature resistance; on this basis, the curvature of adjacent bamboo boards is precisely matched to ensure seamless splicing and uniform penetration of adhesive; S3 stacks the treated bamboo boards in multiple layers in a crisscross order, with each layer of bamboo boards arranged at a 90-degree angle to the previous layer to maximize the overall bending and compression resistance and ensure that the adhesive between each layer is in full contact; S4 is initially pressed at 60-70℃ and 1-1.2MPa for 5-8 minutes, and then the temperature is increased to 125-140℃ and the pressure is 10-14MPa for 18-30 minutes to fully cure the adhesive. The heating should be gradually heated in different areas to ensure that the bamboo board is heated evenly and to prevent the local temperature from being too high or too low. After S5 is completed with hot pressing, the bamboo board is cooled for 5 to 10 minutes, and the pressure is maintained at 4 to 6 MPa to maintain the shape of the board during the cooling process. Then, it is sanded to ensure a smooth surface and remove excess glue. S6 passes multiple tests such as thickness, flatness, and strength to ensure that the finished bamboo panels meet the quality standards for large-size applications.

2. A large-size bamboo board pressing process as claimed in claim 1, It is characterized in that The shape one described in S1 is a horizontal line at the top, forming a right-angled depression downward, extending into a sharp inverted V-shaped groove, forming a right-angled protrusion again, and ending with a short horizontal line to facilitate interlocking with adjacent structures.

3. A large-size bamboo board pressing process as claimed in claim 1, It is characterized in that The second shape described in S1 is a short horizontal line at the top, followed by two right-angled depressions downward, forming a stepped notch structure.

4. A large-size bamboo board pressing process as claimed in claim 1, It is characterized in that The shape three described in S1 is that the interface is in an inclined "S" shape, first convex and then concave, and gradually moves downward.

5. A large-size bamboo board pressing process as claimed in claim 1, It is characterized in that The adhesive described in S2 is isocyanate glue.

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