Three-dimensional protective bamboo composite sleeper and manufacturing method therefor
By forming a three-dimensional structure from unrolled radial bamboo strip units, the problem of low material utilization and poor protective effect of existing bamboo sleepers is solved, achieving high strength, long-lasting protective effect and cost reduction, thus promoting the widespread application of bamboo sleepers.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- HUNAN TAOHUAJIANG BAMBOO SCI & TECH CO LTD
- Filing Date
- 2025-12-31
- Publication Date
- 2026-07-09
AI Technical Summary
Existing bamboo sleepers have low material utilization and high cost during processing, and their protective effect and strength are insufficient, making it difficult to promote and apply them on a large scale.
Radial bamboo strips that have not been rolled or crushed are used to form a three-dimensional structure by bonding them together with an adhesive. The gaps are filled with a protective layer, and the protective layer and the protective layer are connected as one to form a three-dimensional protective effect.
It has improved the utilization rate of bamboo resources, enhanced the protective effect and strength, simplified the processing technology, reduced costs, achieved long-term reliable protection, and promoted the comprehensive application of bamboo railway sleepers.
Smart Images
Figure CN2025147759_09072026_PF_FP_ABST
Abstract
Description
Three-dimensional protective bamboo composite railway sleeper and its manufacturing method
[0001] Cross-references to related applications
[0002] This application is based on and claims priority to two Chinese patent applications, one filed on December 31, 2024, with application number 202411991905.X and entitled "Three-dimensional protective bamboo composite railway sleeper and manufacturing method thereof," and the other filed on December 31, 2024, with application number 202423312067.7 and entitled "Three-dimensional protective bamboo composite railway sleeper." The full text of the two Chinese patent applications is incorporated herein by reference as a part of this application. [Technical Field]
[0003] This invention relates to the field of new materials for railways and urban rail transit, and in particular to a three-dimensional protective bamboo composite sleeper and its manufacturing method. [Background Technology]
[0004] Currently, most ballast tracks in railways and urban rail transit use wooden sleepers, concrete sleepers, steel sleepers, composite material sleepers, etc. Existing sleepers, except for wooden sleepers which require separate surface scoring due to anti-corrosion oiling, generally have a smooth surface due to processing requirements and aesthetics, and are not intentionally made rough. However, wooden sleepers, due to anti-corrosion treatment and oiling, require scoring on all four sides (top, bottom, left, and right) using specialized scoring equipment. This process is complex, costly, and has limited scoring depth.
[0005] Bamboo is an important forest resource in my country, possessing excellent physical and mechanical properties and a wide range of applications. Bamboo has a short growth cycle, maturing in 3-5 years. Existing technologies include methods for making bamboo railway sleepers, such as Chinese patent application CN201910063367.0, which discloses a one-piece molded bamboo railway sleeper and its preparation method. The method involves: 1) Drying and modifying pre-treated bamboo units using superheated steam (10-80 degrees Celsius) until the moisture content is 8-20%, obtaining dried and modified bamboo units; the pre-treatment in step 1) specifically involves removing the bamboo green and yellow parts, steaming to soften, washing, and then crushing to obtain the pre-treated bamboo units; 2) Impregnating the dried and modified bamboo units in step 1) with an adhesive, followed by slaking and extrusion. 1) Dry the bamboo unit until the moisture content is 10% to 16% to obtain a blank; the adhesive is a phenolic resin or modified urea-formaldehyde resin solution with a solid content of 20% to 30%; the impregnation treatment is an ultrasonic pulse-assisted atmospheric pressure treatment, and the pressure during the impregnation treatment is 0.2 to 0.8 MPa; 2) Cur the blank from step 2) at a temperature of 120 to 160°C to obtain a bamboo sleeper blank; 3) Coat the surface of the bamboo sleeper blank from step 3) with a dopamine solution, and then perform anti-mildew and / or anti-corrosion and / or anti-insect treatment to obtain a bamboo sleeper; the anti-mildew and / or anti-corrosion and / or anti-insect treatment specifically involves: coating the surface of the bamboo sleeper blank with a dopamine solution and drying it, first coating it with a titanium sulfate solution, drying it, then coating it with a silver nitrate solution, and drying it to obtain a bamboo sleeper; 4) Secure the bamboo sleeper from step 4) with fasteners to obtain a one-piece molded bamboo sleeper. The applicant discovered the following technical problems with the proposed solution: ① The bamboo unit removes the green and yellow parts of the bamboo, resulting in low material utilization, high cost, and difficulty in large-scale application; ② The protective treatment process is too complex and costly. Using bamboo fibers as the unit, the process involves rolling and then impregnating with resin to solidify the bamboo. Rolling the bamboo fibers damages the strength of the bamboo fibers themselves. After rolling and pressing, the bamboo sleeper blank has virtually no gaps (or grooves) inside, making it difficult for the protective solution to penetrate, bind, and coat the bamboo sleeper during subsequent protective treatment. This leads to the bamboo sleeper's protective effect failing after a period of use. Therefore, the existing bamboo sleeper still suffers from technical problems such as damage to the raw material strength, poor long-term protective effect, low strength, and high cost, which limits its widespread industrial application. [Summary of the Invention]
[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a three-dimensional protective bamboo composite sleeper with durable protection and high strength suitable for ballast tracks of railways and urban rail transit, as well as its manufacturing method.
[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0008] A three-dimensional protective bamboo composite railway sleeper includes a bamboo sleeper base and a protective layer. The protective layer is wrapped around the bamboo sleeper base. The bamboo sleeper base includes multiple radial bamboo strip units that have not been rolled or crushed and multiple gaps. Each radial bamboo strip unit is wrapped with an adhesive and the radial bamboo strip units are bonded together by the adhesive. The gaps are formed between at least two radial bamboo strip units and the gaps are filled with a protective body. The protective body is connected to the protective layer as a whole.
[0009] In some embodiments of the present invention, the adhesive is formed by immersing radial bamboo strip units in an adhesive for a preset time, drying them, and then pressing and curing them.
[0010] In some embodiments of the present invention, the moisture content of the radial bamboo strip unit is 8% to 20%.
[0011] In some embodiments of the present invention, the bamboo sleeper base is obtained by first pressing radial bamboo strip units to a preset pressure, then heating them to a preset temperature, and then curing them for a preset time.
[0012] In some embodiments of the present invention, the preset temperature is 100℃~165℃.
[0013] In some embodiments of the present invention, the preset pressure is 10MPa to 30MPa.
[0014] In some embodiments of the present invention, the protective layer and the protective body are made of the same or different materials; when the materials are the same, the protective layer and the protective body are protective coating structures formed by immersing the bamboo sleeper substrate in protective coating for a predetermined time; when the materials are different, the protective layer and the protective body are step-by-step integral structures formed by first filling the gap with the protective body and then wrapping the bamboo sleeper substrate with the protective layer.
[0015] In some embodiments of the present invention, the upper part of the bamboo sleeper base is provided with a support portion for supporting the fixed track.
[0016] In some embodiments of the present invention, the radial bamboo strip units are arranged in a disordered manner, so that the protective body forms a three-dimensional mesh structure.
[0017] In some embodiments of the present invention, the bamboo sleeper base is rectangular in shape, and the radial bamboo strip units are arranged longitudinally.
[0018] As a general inventive concept, the present invention also provides a method for manufacturing a three-dimensional protective bamboo composite railway sleeper, comprising the following steps:
[0019] S1. The original bamboo, retaining both the green and yellow parts, is radially split and dried to obtain radial bamboo strip units;
[0020] S2. The radial bamboo strip units are immersed in an adhesive with a solid content of 28% to 60% without being crushed or pressed. After the adhesive is applied, the radial bamboo strip units are dried until the moisture content of the radial bamboo strip units is 8% to 20%. After obtaining the adhesive, the radial bamboo strip units are dried.
[0021] S3. The dried radial bamboo strip units after gluing are assembled in a mold, and pressure is applied to press the dried radial bamboo strip units together to obtain a pressed blank.
[0022] S4. The pressed blank is cured at a temperature of 100-165℃. After curing, the mold is removed to obtain the bamboo sleeper blank. There are gaps between the radial bamboo strip units inside the bamboo sleeper blank.
[0023] S5. Process the bamboo sleeper blank into the target size and shape to obtain the bamboo sleeper base;
[0024] S6. The bamboo sleeper substrate is directly subjected to protective treatment without scoring, resulting in a three-dimensional protective bamboo composite sleeper. The surface of the bamboo sleeper substrate has a protective layer formed by protective coating, and the gaps inside the bamboo sleeper substrate have a protective body formed by protective coating.
[0025] In some embodiments of the present invention, in step S1, the thickness of the radial bamboo strip unit is 0.5mm to 3mm, and the width is 3mm to 12mm.
[0026] In some embodiments of the present invention, preferably, the thickness of the radial bamboo strip unit is 0.5 mm to 2 mm.
[0027] In some embodiments of the present invention, in step S2, the adhesive is one or more of phenolic resin, isocyanate, polyurethane, resorcinol, and urea-formaldehyde resin with a solid content of 28% to 60%.
[0028] In some embodiments of the present invention, preferably, when the adhesive is a phenolic resin, the solid content of the phenolic resin is 29% to 55%.
[0029] In some embodiments of the present invention, the pressure in step S3 is 10 MPa to 30 MPa.
[0030] In some embodiments of the present invention, during step S4, the curing time is 2h to 12h.
[0031] In some embodiments of the present invention, in step S5, the target size is a length of 2000mm to 5000mm, a width of 200mm to 300mm, and a thickness of 130mm to 300mm.
[0032] In some embodiments of the present invention, step S6 includes the following steps: coating the surface of the bamboo sleeper substrate with a protective coating and penetrating it into the internal gaps of the bamboo sleeper substrate; the protective coating is one or more of polyurea coating, styrene-acrylic coating, silicone-acrylic coating, etc.
[0033] In some embodiments of the present invention, in step S6, the protective processing is at least one of feature A to feature C:
[0034] A. Immerse the bamboo sleeper base in a protective coating at normal pressure;
[0035] B. Impregnate the bamboo sleeper base with protective coating under pressure;
[0036] C. Apply protective coating to the bamboo sleeper base.
[0037] Preferably, in some embodiments of the present invention, the protective treatment is carried out in multiple steps, such as first immersing the bamboo sleeper substrate in a protective coating under normal pressure or pressure, drying it, and then applying the protective coating to the bamboo sleeper substrate.
[0038] In some embodiments of the present invention, the protective coating is difficult to penetrate into the gaps inside the bamboo sleeper substrate in a single application, and needs to be applied to the bamboo sleeper substrate multiple times. In this way, the protective coating can easily penetrate into the gaps inside the bamboo sleeper substrate.
[0039] In some embodiments of the present invention, in step S6, the protective layer on the surface of the bamboo sleeper base and the protective body in the gap inside the bamboo sleeper base are integrally formed to form a three-dimensional network protective structure.
[0040] In some embodiments of the present invention, protective coating is filled in some gaps inside the bamboo sleeper base; preferably, protective coating is filled in all gaps inside the bamboo sleeper base.
[0041] In some embodiments of the present invention, steps S1 and S2 further include carbonizing the radial bamboo strip units at a temperature of 120–140°C for 1–3 hours.
[0042] Compared with the prior art, the advantages of the present invention are as follows:
[0043] The three-dimensional protective bamboo composite railway sleeper of the present invention has the following characteristics: First, the surface of the radial bamboo strip units is not subjected to rolling or pressing treatment, which does not damage the strength of the bamboo fiber itself and facilitates the penetration and wrapping of the protective body in the gaps between the radial bamboo strip units, thereby improving the protective effect of the protective body; Second, the bamboo sleeper base includes multiple gaps, which are formed between at least two radial bamboo strip units. The gaps are filled with the protective body, and the protective body is connected to the protective layer as a whole, so that the protective body in the bamboo sleeper base and the protective layer wrapped around the bamboo sleeper base are integrated to form a three-dimensional protective effect. The protective layer is not easy to fall off, the protection time is long, and the overall strength is high.
[0044] The present invention discloses a method for preparing a three-dimensional protective bamboo composite railway sleeper. The radial bamboo strip units are not subjected to rolling or pressing treatment. On the one hand, the radial bamboo strip units are not subjected to rolling or pressing treatment, which can maximize the preservation of the bamboo's own strength and achieve the maximum resource utilization rate of bamboo resources. The utilization rate of raw bamboo is increased from 30% to more than 90%. This avoids the damage to the fiber strength of bamboo fibers caused by rolling during the ordinary reconstituted bamboo processing. Compared with bamboo bundle units bamboo sleepers made of ordinary bamboo fibers, it has greater mechanical strength, lower price, and simpler operation process. On the other hand, when radial bamboo strip units that have not undergone rolling or pressing are pressed, because they have not been rolled, individual radial bamboo strip units are not easily compressed during assembly and pressing. Furthermore, the radial bamboo strip units do not adhere as tightly and densely as rolled bamboo filament units. During pressing, gaps (or grooves) can form between the radial bamboo strip units, facilitating the deep bonding, filling, penetration, and encapsulation of the protective coating with the bamboo material during subsequent protective treatment. This enhances adhesion and bonding strength, achieving a long-term reliable protective effect without the need for special scoring before protective treatment. This significantly promotes the widespread application of bamboo strip units and bamboo material in bamboo-made railway sleepers. Therefore, the composite bamboo railway sleeper of this invention not only improves strength but also significantly reduces the price of existing reconstituted bamboo railway sleepers, preventing price issues from hindering the large-scale application of bamboo railway sleepers. This plays a crucial role in promoting the comprehensive application of bamboo railway sleepers. [Attached Image Description]
[0045] Figure 1 is a process flow diagram of the present invention.
[0046] Figure 2 is a photograph of the radial bamboo strip unit in Embodiment 1 of the present invention.
[0047] Figure 3 is a three-dimensional structural diagram of the three-dimensional protective bamboo composite sleeper in Embodiment 1 of the present invention.
[0048] Figure 4 is a schematic diagram of the cross-sectional structure of AA in Figure 3.
[0049] Figure 5 is an enlarged view of point B in Figure 4.
[0050] Figure 6 is a schematic diagram of the three-dimensional structure of the bamboo sleeper base of the three-dimensional protective bamboo composite sleeper.
[0051] Figure 7 is a side view of the bamboo sleeper base of the three-dimensional protective bamboo composite sleeper.
[0052] Figure 8 is a structural schematic diagram of another embodiment of the three-dimensional protective bamboo composite sleeper.
[0053] Figure 9 is a physical image of the bamboo sleeper base of the three-dimensional protective bamboo composite sleeper.
[0054] Figure 10 is a photograph of the bamboo bundle unit used in Comparative Example 1 of the present invention.
[0055] Legend: 1. Bamboo sleeper base; 11. Radial bamboo strip unit; 12. Gap; 13. Adhesive body; 14. Protective body; 2. Protective layer; 3. Bearing part.
Detailed Implementation Methods
[0056] Example 1
[0057] Taking the manufacture of a bamboo rail sleeper with a width of 220mm, a thickness of 160mm, and a length of 2500mm as an example, as shown in Figure 1, the manufacturing method of a three-dimensional protective bamboo composite rail sleeper in this embodiment specifically includes the following steps:
[0058] (1) Select 5-year-old moso bamboo and cut it in the length direction. Each section is 2500mm±10mm to obtain the original bamboo section.
[0059] (2) Split the original bamboo section into an arc-shaped bamboo unit that retains the green bamboo and the yellow bamboo. Then process the arc-shaped bamboo unit that retains the green bamboo and the yellow bamboo into a radial bamboo strip unit 11 with a length of 2500mm, a width of 10mm and a thickness of 1.5mm using a radial bamboo strip splitting machine, as shown in Figure 2. Figure 2(a) is an actual end view of the radial bamboo strip unit 11, and Figure 2(b) is an actual top view of the radial bamboo strip unit 11. It can be seen from the figures that the radial bamboo strip unit 11 has not been crushed and includes the green bamboo part, the bamboo flesh part and the yellow bamboo part.
[0060] In this embodiment, the radial bamboo strip unit 11 is not carbonized. Without protective treatment, the weather resistance will not reach the strong corrosion resistance level I. However, the present invention performs protective treatment in the future. The protective coating covers the bamboo sleeper substrate 1, isolating external moisture and not affecting the overall weather resistance.
[0061] The radial bamboo strip unit 11 of the present invention has a thickness of 0.5mm to 3mm and a width of 3mm to 12mm, which can achieve the same or similar technical effects. Within this size range of the radial bamboo strip unit 11, the bamboo flesh part of the radial bamboo strip unit 11 is actually used as the main bonding surface. The bonding area of the bamboo green part and the bamboo yellow part is small, so it is not necessary to crush it into bamboo bundle units to achieve bonding, and the impact on bonding performance is small.
[0062] (3) The above-mentioned radial bamboo strip unit 11 is dried with hot air at 100°C until the moisture content is about 10%.
[0063] (4) The dried radial bamboo strip unit 11 is immersed in phenolic resin with a solid content of 29% for 20 minutes under normal pressure to absorb the glue. During the immersion, the glue is kept flowing to ensure the uniformity of the glue. After immersion, the excess adhesive is drained off, and then dried at 60°C until the moisture content of the radial bamboo strip unit 11 is 8% to 20%, thus obtaining the glued and dried radial bamboo strip unit 11.
[0064] In other embodiments, the sizing treatment can be carried out under a pressure of 0.2 to 0.8 MPa for 10 to 15 minutes to achieve the same or similar technical effects.
[0065] (5) The dried radial bamboo strip units 11 are assembled in a mold of matching size and pressure is applied at 25 MPa to ensure that the bamboo strip units are fully pressed and bonded together, so as to ensure the curing and bonding of the adhesive in the subsequent process. The pressure of this invention is 10-30 MPa. If the pressure is too low, such as 5 MPa, the radial bamboo strip units 11 will not be bonded tightly and the bonding performance will be poor. In severe cases, the pressing and forming will fail and the boards may even fall apart (the radial bamboo strip units 11 will separate and cannot be bonded together). If the pressure is too high, such as 40 MPa, the radial bamboo strip units 11 will be bonded too tightly and the internal gaps 12 will be too small, which will affect the deep penetration of the protective coating in the subsequent steps and ultimately affect the three-dimensional protective effect.
[0066] Since the present invention requires gaps 12 (or grooves) to be left between the radial bamboo strip units 11 so that the protective coating can penetrate into the interior of the bamboo sleeper base 1, there is no requirement for the radial bamboo strip units 11 to be sorted and aligned during assembly, and the radial bamboo strip units 11 are arranged randomly.
[0067] (6) The blank pressed by the mold is cured at 150°C for 4 hours. After curing, the mold is removed to obtain the bamboo sleeper blank.
[0068] (7) The bamboo sleeper blank is first machined to measure its length, width and thickness. In this embodiment, the bamboo sleeper is machined to be 2500mm long, 220mm wide and 160mm thick. Then it is shaped and drilled to obtain the bamboo sleeper base 1. Drilling is to make holes in the bamboo sleeper for fixing bolts to facilitate the installation of rails.
[0069] The product in this embodiment is a regular cuboid with no need for special scoring on the surface. The diameter of the fixing bolt holes is 22mm to meet the requirements for sleeper size, appearance and installation.
[0070] (8) Use a highly waterproof, highly weather-resistant, and highly elastic polyurea coating (commercially available) to penetrate, combine, and wrap the machined bamboo sleeper substrate 1 under normal pressure to form an integrated protective layer for overall protection. The treatment needs to be done in all aspects to obtain a three-dimensional protective bamboo composite sleeper, as shown in Figures 3, 6, and 9.
[0071] The present invention discloses a method for manufacturing a three-dimensional protective bamboo composite railway sleeper. Raw bamboo retaining both its green and yellow layers is processed into radial bamboo strip units 11. Radial bamboo strips that do not require removal of the green and yellow layers are recombined and utilized. During the curing and pressing process, gaps 12 (or grooves) naturally form between the radial bamboo strip units 11 without undergoing rolling treatment. This facilitates the bonding, filling, penetration, and encapsulation of the protective coating with the bamboo material during subsequent protective treatment, enhancing adhesion and bonding strength, and achieving a long-term reliable protective effect. This eliminates the need for additional scoring processes to allow the protective coating to penetrate, improving the protective treatment effect while simplifying the process and reducing processing costs.
[0072] In this invention, since the radial bamboo strip units 11 are not rolled, individual radial bamboo strip units 11 are not easily compressed during assembly and pressing. Furthermore, the radial bamboo strip units 11 are not as tightly and densely bonded as rolled bamboo filament units. Therefore, when the three-dimensional protective bamboo composite sleeper adhesive is pressed onto the surface of the radial bamboo strip units 11, gaps 12 (or grooves) can be formed inside the radial bamboo strip units 11. The gaps 12 (or grooves) are not completely filled with adhesive. During subsequent protective treatment, the protective coating can penetrate into the gaps 12 (or grooves) inside the already pressed bamboo sleeper base 1, and the gaps 12 (or grooves) are filled, penetrated, bonded, and wrapped with the protective coating. The existing rolled bamboo bundle unit fiber structure is destroyed, and it is easy to compress and tightly fit during pressing. There are basically no gaps 12 (or grooves) between the bamboo bundle units, which does not meet the objective conditions for filling the bamboo sleeper base 1 with penetrating protective coating. The unrolled radial bamboo strip unit 11 of this invention and the existing rolled bamboo bundle unit have two different structures after pressing. The existence of internal gaps 12 (or grooves) makes it easier for the protective coating to penetrate deeply and build a three-dimensional network protective structure.
[0073] In other embodiments, protective treatment is carried out under pressure immersion at a pressure of 0.6 to 1.2 MPa, which can be completed in a shorter time (normal pressure immersion requires 15 to 20 minutes, while pressure immersion only requires 5 to 10 minutes), and the same or similar technical effects can be achieved.
[0074] In this embodiment, a three-dimensional protective bamboo composite sleeper is manufactured by using radial bamboo strips that retain both the green and yellow parts of the bamboo, through a combination of multiple technologies including gluing, post-gluing drying, pressing, thermosetting, machining, and surface protection treatment. The specific process flow of this embodiment is as follows: cutting the raw bamboo → splitting the raw bamboo segments → radial splitting → drying the radial bamboo strip unit 11 → impregnating with phenolic resin → post-gluing drying → assembling the blank → pressing → thermosetting → machining → integrated surface protection treatment → three-dimensional protective bamboo composite sleeper.
[0075] As shown in Figures 3 to 9, the three-dimensional protective bamboo composite sleeper of this embodiment includes a bamboo sleeper base 1 and a protective layer 2. The protective layer 2 is wrapped around the bamboo sleeper base 1. The bamboo sleeper base 1 includes multiple radial bamboo strip units 11 that have not been rolled or crushed and multiple gaps 12. Each radial bamboo strip unit 11 is wrapped with an adhesive 13. Each radial bamboo strip unit 11 is bonded together by the adhesive 13. The gaps 12 are formed between at least two radial bamboo strip units 11. The gaps 12 are filled with a protective body 14. The protective body 14 is connected to the protective layer 2 as a whole.
[0076] The three-dimensional protective bamboo composite railway sleeper of the present invention has the following characteristics: First, the surface of the radial bamboo strip units 11 is not subjected to rolling or pressing treatment, which does not damage the strength of the bamboo fiber itself and facilitates the penetration and wrapping of the protective body 14 into the gaps 12 between the radial bamboo strip units 11, thereby improving the protective effect of the protective body 14. Second, the bamboo sleeper base 1 includes multiple gaps 12, which are formed between at least two radial bamboo strip units 11. The gaps 12 are filled with the protective body 14, and the protective body 14 is connected to the protective layer 2 as a whole, so that the protective body 14 inside the bamboo sleeper base 1 is combined with the protective layer 2 wrapped around the bamboo sleeper base 1 to form a three-dimensional protective effect. The protective layer 2 is not easy to fall off, the protection time is long, and the overall strength is high.
[0077] Furthermore, in this embodiment, the adhesive 13 on the surface of the radial bamboo strip unit 11 is formed by immersing the radial bamboo strip unit 11 in the adhesive for a preset time, drying it, and then pressing and curing it, which helps to improve the overall bonding strength. Preferably, the adhesive 13 is a phenolic resin, which has good bonding effect and good weather resistance, and helps to improve the overall bonding strength.
[0078] Furthermore, as shown in Figures 6, 7, and 9, in this embodiment, the bamboo sleeper base 1 is obtained by first pressing the assembled radial bamboo strip units 11 to a preset pressure, then heating them to a preset temperature, and finally curing them for a preset time. This process is convenient and has high production efficiency. Further, the preset temperature is 100℃~165℃, and the preset pressure is 10MPa~30MPa.
[0079] In other embodiments of the present invention, the protective layer 2 and the protective body 14 may be made of the same or different materials. When the materials are the same, the protective layer 2 and the protective body 14 are protective coating structures formed by immersing the bamboo sleeper substrate 1 in a protective coating for a predetermined time. When the materials are different, the protective layer 2 and the protective body 14 are step-by-step integral structures formed by first filling the gap 12 with the protective body 14 and then wrapping the bamboo sleeper substrate 1 with the protective layer 2. Preferably, the protective layer 2 and the protective body 14 are made of polyurea coating. In this case, the protective layer 2 and the protective body 14 are polyurea coating structures formed by immersing the bamboo sleeper substrate 1 in polyurea coating for a predetermined time. The protective layer 2 and the protective body 14 are formed in one step by immersing the bamboo sleeper substrate 1 in polyurea coating for a predetermined time, which is convenient to produce and has a good protective effect.
[0080] Furthermore, in this embodiment, the radial bamboo strip units 11 are arranged randomly, so that the protective body 14 forms a three-dimensional mesh structure, which further improves the protective effect.
[0081] Furthermore, in this embodiment, the bamboo sleeper base 1 is rectangular in shape, and the radial bamboo strip units 11 can be arranged longitudinally.
[0082] In some embodiments of the present invention, the upper part of the bamboo rail sleeper base 1 is provided with a support part 3 for supporting and fixing the rail, as shown in FIG8. The support part 3 is provided with threaded holes for fixing the rail with bolts.
[0083] Example 2
[0084] Taking the manufacture of a bamboo rail sleeper with a width of 220mm, a thickness of 160mm, and a length of 2500mm as an example, this embodiment of a method for manufacturing a three-dimensional protective bamboo composite rail sleeper specifically includes the following steps:
[0085] (1) Select 5-year-old moso bamboo and cut it in the length direction. Each section is 2500mm+10mm long to obtain the original bamboo section.
[0086] (2) Split the original bamboo section into an arc-shaped bamboo unit that retains the green and yellow bamboo, and then process the arc-shaped bamboo unit that retains the green and yellow bamboo into a radial bamboo strip unit 11 with a length of 2500mm, a width of 10mm and a thickness of 1.5mm using a radial bamboo strip splitting machine.
[0087] (3) Carbonize the above-mentioned radial bamboo strip unit 11 at 130℃ for 2 hours to further improve its anti-corrosion and anti-mildew properties, so that its anti-corrosion performance reaches the strong corrosion resistance level I.
[0088] (4) The above-mentioned radial bamboo strip unit 11 is dried with hot air at 100°C until the moisture content is about 10%.
[0089] (5) The dried radial bamboo strip unit is immersed in phenolic resin with a solid content of 29% for 20 minutes under normal pressure to absorb the glue. During the immersion, the glue is kept flowing to ensure the uniformity of the glue. After immersion, the excess adhesive is drained off, and then dried at 60°C until the moisture content of the radial bamboo strip unit 11 is 8% to 20%, thus obtaining the glued and dried radial bamboo strip unit 11.
[0090] (6) The dried radial bamboo strip units 11 after gluing are assembled in a mold of matching size and pressure is applied at a pressure of 25 MPa to ensure that the bamboo strip units are fully pressed and bonded together to ensure the curing and bonding of the adhesive.
[0091] (7) The blank pressed by the mold is cured at 150°C for 4 hours. After curing, the mold is removed to obtain the bamboo sleeper blank.
[0092] (8) The bamboo sleeper blank is first machined to measure its length, width and thickness. In this embodiment, the bamboo sleeper is machined to be 2500mm long, 220mm wide and 160mm thick. Then it is shaped and drilled to obtain the bamboo sleeper base 1. Drilling is to make holes in the bamboo sleeper for fixing bolts to facilitate the installation of rails.
[0093] In this embodiment, the shape is a regular cuboid and the surface does not require special scoring treatment. The diameter of the hole for fixing bolts is 22mm to meet the requirements for sleeper size, appearance and installation.
[0094] (9) The bamboo sleeper substrate 1 that has been machined is subjected to pressure impregnation with a high waterproof, high weather-resistant and high elastic polyurea coating to penetrate, combine and wrap to form an integrated protective layer for overall protection treatment. The treatment is carried out under a pressure of 0.6MPa for 10 minutes to further improve the penetration depth of the protective treatment and ensure that the treatment is in place in all aspects, so as to obtain a three-dimensional protective bamboo composite sleeper.
[0095] In this embodiment, a three-dimensional protective bamboo composite sleeper is manufactured by using radial bamboo strips that retain both the green and yellow parts of the bamboo, through a combination of multiple technologies including carbonization, drying, gluing, post-glue drying, pressing, thermosetting, machining, and surface protection treatment. The specific process flow of this embodiment is as follows: cutting the raw bamboo → splitting the raw bamboo segments → radial splitting → carbonizing the radial bamboo strip unit 11 → drying the radial bamboo strip unit 11 → impregnating with phenolic resin → post-glue drying → assembling the blank → pressing → thermosetting → machining → integrated surface protection treatment → three-dimensional protective bamboo composite sleeper.
[0096] Example 3
[0097] Taking the manufacture of a bamboo rail sleeper with a width of 220mm, a thickness of 160mm, and a length of 2500mm as an example, this embodiment of a method for manufacturing a three-dimensional protective bamboo composite rail sleeper specifically includes the following steps:
[0098] (1) Select 5-year-old moso bamboo and cut it in the length direction. Each section is 2500mm+10mm long to obtain the original bamboo section.
[0099] (2) Split the original bamboo section into an arc-shaped bamboo unit that retains the green and yellow bamboo, and then process the arc-shaped bamboo unit that retains the green and yellow bamboo into a radial bamboo strip unit 11 with a length of 2500mm, a width of 10mm and a thickness of 1.2mm using a radial bamboo strip splitting machine.
[0100] (3) Carbonizing the above-mentioned radial bamboo strip unit 11 at 130℃ for 2 hours further improves its anti-corrosion and anti-mildew properties, so that its anti-corrosion performance reaches the strong corrosion resistance level I. If the protective layer 2 of the bamboo sleeper is damaged, the anti-corrosion and anti-mildew effect of the bamboo composite sleeper made of the carbonized radial bamboo strip unit 11 will be better than that of the bamboo composite sleeper made of the uncarbonized radial bamboo strip unit 11 in Example 1.
[0101] (4) The above-mentioned radial bamboo strip unit 11 is dried with hot air at 100°C until the moisture content is about 10%.
[0102] (5) The dried radial bamboo strip unit 11 is immersed in a commercially available conventional (produced by Taier Adhesive (Guangdong) Co., Ltd.) modified isocyanate adhesive with a solid content of 35% for 20 minutes under normal pressure to absorb the adhesive. During immersion, the adhesive is kept flowing to ensure the uniformity of the adhesive. After immersion, excess adhesive is drained off, and then dried at 60°C until the moisture content of the radial bamboo strip unit 11 is 8% to 20%, thus obtaining the dried radial bamboo strip unit 11 after adhesive treatment.
[0103] (6) The dried radial bamboo strip units 11 after gluing are assembled in a mold of matching size and pressure is applied. The pressure is 25 MPa to ensure that the bamboo strip units are fully pressed and bonded to ensure the subsequent curing and bonding of the adhesive, resulting in a pressed blank.
[0104] (7) The blank pressed by the mold is cured at 130°C for 10 hours. After curing, the mold is removed to obtain the bamboo sleeper blank.
[0105] (8) The bamboo sleeper blank is first machined to measure its length, width and thickness. In this embodiment, the bamboo sleeper is machined to be 2500mm long, 220mm wide and 160mm thick. Then it is shaped and drilled to obtain the bamboo sleeper base 1.
[0106] In this embodiment, the shape is a regular cuboid and the surface does not require special scoring treatment. The diameter of the hole for fixing bolts is 22mm to meet the requirements for sleeper size, appearance and installation.
[0107] (9) The bamboo sleeper substrate 1 that has been machined is subjected to pressure impregnation with a high waterproof, high weather-resistant and high elastic polyurea coating to penetrate, combine and wrap to form an integrated protective layer for overall protection treatment. The treatment is carried out under a pressure of 0.6MPa for 10 minutes to further improve the penetration depth of the protective treatment and ensure that the treatment is in place in all aspects, so as to obtain a three-dimensional protective bamboo composite sleeper.
[0108] In this embodiment, a three-dimensional protective bamboo composite sleeper is manufactured by using radial bamboo strips that retain both the green and yellow parts of the bamboo, through a combination of multiple technologies including carbonization, drying, gluing, post-gluing drying, pressing, thermosetting, machining, and surface protection treatment.
[0109] The specific process flow of this embodiment is as follows: cutting the raw bamboo → splitting the raw bamboo segments → radial splitting → carbonizing the radial bamboo strip unit 11 → drying the radial bamboo strip unit 11 → impregnating with modified isocyanate adhesive → drying after adhesive application → assembling → pressing → thermosetting → machining → integrated surface protection treatment → three-dimensional protective bamboo composite sleeper.
[0110] Example 4
[0111] The manufacturing method of this embodiment is the same as that of embodiment 1. The difference is that in step (8) of this embodiment, the highly waterproof, highly weather-resistant, and highly elastic polyurea coating (commercially available) is applied to the machined bamboo rail sleeper substrate 1 multiple times (twice in this embodiment) to penetrate, combine, and wrap it to form an integrated protective layer for overall protection.
[0112] The anti-corrosion and anti-mildew performance of the composite bamboo sleeper product in this embodiment is the same as that in Embodiment 1, reaching the highest level. However, after the protective layer 2 on the surface of the product is damaged, because Embodiment 4 only uses coating for protection, the gaps 12 in the core of the bamboo sleeper substrate 1 are difficult for the protective coating to penetrate deeply. When the surface protective layer 2 of the products in Embodiments 1 and 4 is damaged to the same extent, the anti-corrosion, anti-mildew, and waterproof performance of the product in Embodiment 4 is inferior to that in Embodiment 1. This indicates that compared to coating for protection, pressure impregnation and atmospheric pressure immersion are more conducive to the deep penetration of the protective coating into the bamboo sleeper substrate 1, resulting in better protection durability.
[0113] Comparative Example 1
[0114] Taking the manufacture of a bamboo rail sleeper with a width of 220mm, a thickness of 160mm, and a length of 2500mm as an example, the manufacturing method of this comparative example of a rolled bamboo bundle reconstituted bamboo three-dimensional protective bamboo composite rail sleeper specifically includes the following steps:
[0115] (1) Select 5-year-old moso bamboo and cut it in the length direction. Each section is 2500mm+10mm long to obtain the original bamboo section.
[0116] (2) The original bamboo segments are split into arc-shaped bamboo units that retain the green and yellow parts of the bamboo. The green and yellow parts of the bamboo units are removed from the surface of the arc-shaped bamboo units. The arc-shaped bamboo units are then rolled into bamboo bundle units that are 2500 mm long, 30 mm wide, and 6.5 mm thick, as shown in Figure 10. Figure 10(a) is an end view of the rolled bamboo bundle unit, and Figure 10(b) is a top view of the rolled bamboo bundle unit. This shows that the bamboo bundle unit is cracked and broken inside and on the surface, and does not have the strength of the unrolled bamboo unit.
[0117] (3) Carbonize the above bamboo bundle units at 130℃ for 2 hours to further improve their anti-corrosion and anti-mildew properties, so that their anti-corrosion performance reaches the strong corrosion resistance level I.
[0118] (4) The bamboo bundle units are dried with hot air at 100°C until the moisture content is about 10%.
[0119] (5) The dried bamboo bundle unit is immersed in phenolic resin with a solid content of 25% for 20 minutes under normal pressure to absorb the glue. During the immersion, the glue is kept flowing to ensure the uniformity of the glue. After immersion, the excess adhesive is drained off, and then dried at 60°C until the moisture content of the radial bamboo strip unit 11 is 8% to 20%, thus obtaining the glued and dried radial bamboo strip unit 11.
[0120] In other comparative examples, the sizing treatment can be carried out under a pressure of 0.2 to 0.8 MPa for 10 to 15 minutes to achieve the same or similar technical results.
[0121] (6) Assemble the dried bamboo bundle units after gluing in a mold of matching size and apply pressure of 25 MPa to ensure that the bamboo bundle units are fully pressed and bonded together to ensure the subsequent curing and bonding of the adhesive.
[0122] (7) The blank pressed by the mold is cured at 150°C for 4 hours. After curing, the mold is removed to obtain the bamboo sleeper blank.
[0123] (8) The bamboo sleeper blank is first machined to measure its length, width and thickness. The bamboo sleeper in this comparative example is machined to be 2500mm long, 220mm wide and 160mm thick. Then it is shaped and drilled to obtain the bamboo sleeper base 1. The drilling is to make holes for fixing bolts on the bamboo sleeper base 1 to facilitate the installation of rails.
[0124] This comparative model is a standard cuboid, with the fixing bolt holes having a diameter of 22mm to meet the requirements for sleeper size, appearance, and installation.
[0125] (9) Use a scoring machine to score the four sides of the machined bamboo rail sleeper base 1, with a scoring depth of about 10mm.
[0126] (10) The bamboo sleeper substrate 1, which has been machined and scored, is treated with a high-waterproof, high-weather-resistant, and high-elasticity polyurea coating. The coating is impregnated under pressure to penetrate, combine, and wrap the substrate to form an integrated protective layer for overall protection. The coating is treated for 10 minutes under a pressure of 0.6 MPa to further improve the penetration depth of the protective treatment and ensure that the treatment is carried out in all aspects. This results in a three-dimensional protective bamboo composite sleeper with bamboo bundle units.
[0127] The specific steps of this comparative example are as follows: cutting the raw bamboo → splitting the raw bamboo segments → removing the green and yellow parts from the arc-shaped bamboo units → rolling the bamboo bundle units → carbonizing the bamboo bundle units → drying the bamboo bundle units → impregnating with phenolic resin → drying after resin application → assembling the blanks → pressing → thermosetting → machining → surface scoring treatment → integrated surface protection treatment → three-dimensional protective bamboo composite sleeper with bamboo bundle units.
[0128] In this comparative example, the bamboo bundle units require the removal of green and yellow materials, resulting in low material utilization. Furthermore, the bamboo fibers are damaged by being crushed. When the bamboo bundles are pressed together, the bamboo bundle units inside the sleeper are tightly connected with virtually no gaps.12 Therefore, it is difficult to penetrate, bond, and wrap the bamboo bundles during the final overall protective treatment. Without specialized scoring, the integrated protective layer will have a poor bonding effect. Even if scoring is applied to the surface to increase the protective effect, the protective effect is only on the surface and does not include the core layer of the bamboo sleeper in a three-dimensional protective treatment. In other words, it cannot achieve deep and complete penetration, bonding, and wrapping.
[0129] Performance tests were conducted on the composite sleepers of Example 1 and Comparative Example 1. The results showed that Example 1 performed better than Comparative Example 1, specifically in the following ways: ① High strength: The three-dimensional protective bamboo composite sleeper of Example 1, with the same cross-section and thickness (20mm thick test specimen), exhibited a bending strength more than 25% higher than that of the bamboo bundle three-dimensional protective bamboo composite sleeper of Comparative Example 1. The average bending strength of the sample specimens from Example 1 reached 190MPa, and the bending elastic modulus was 15500MPa, while the average bending strength of the sample specimens from the Comparative Example was approximately 150MPa, and the bending elastic modulus was 12500MPa. ② Weather resistance: Both examples achieved the highest levels of corrosion and mildew resistance (Level I and Level 0). However, Example 1's method was simpler and more convenient, with lower costs, a longer-lasting integrated protective coating, and a water softening coefficient greater than 0.85. Overall, Example 1 offered lower costs and better performance.
[0130] Comparative Example 2
[0131] The preparation method of the reconstituted material in this comparative example is roughly the same as that in Example 2, except that the adhesive used in step (5) of this comparative example is 22% phenolic resin adhesive.
[0132] In Comparative Example 2, the reconstituted material exhibited an expansion rate exceeding 25% during a 2-hour boiling water thickness expansion test, with some radial bamboo strip units 11 peeling off from the product. This indicates that Comparative Example 2 had poor bonding performance and did not meet the performance requirements for outdoor use. In contrast, the composite bamboo sleeper in Example 2 of this invention had an expansion rate of less than or equal to 8%, and no radial bamboo strip units 11 peeled off from the product, meeting the performance requirements for outdoor use. Because the radial bamboo strip units 11 did not undergo rolling and glue absorption, the adhesive penetration was poor. If a low-solids phenolic resin adhesive (e.g., 25% or less) was used, the adhesive contained a large amount of water. During glue absorption, because the molecular weight of water molecules is smaller than that of the adhesive, water was preferentially absorbed. After drying, the water evaporated, resulting in a low actual effective glue absorption amount for the radial bamboo strip units 11. This was detrimental to subsequent bonding, leading to poor bonding effects. In severe cases, the material failed to be pressed into shape and may even scatter (the radial bamboo strip units 11 scattered and unable to be glued together).
[0133] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.
Claims
1. A three-dimensional protective bamboo composite railway sleeper, characterized in that: The system includes a bamboo sleeper base (1) and a protective layer (2). The protective layer (2) is wrapped around the bamboo sleeper base (1). The bamboo sleeper base (1) includes multiple radial bamboo strip units (11) that have not been rolled or crushed and multiple gaps (12). Each radial bamboo strip unit (11) is wrapped with an adhesive (13). Each radial bamboo strip unit (11) is bonded together by the adhesive (13). The gaps (12) are formed between at least two radial bamboo strip units (11). The gaps (12) are filled with a protective body (14). The protective body (14) is connected to the protective layer (2) as a whole.
2. The three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: The adhesive (13) is formed by immersing the radial bamboo strip unit (11) in the adhesive for a preset time, drying it, and then pressing and curing it.
3. The three-dimensional protective bamboo composite sleeper according to claim 2, characterized in that: The moisture content of the radial bamboo strip unit (11) is 8% to 20%.
4. The three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: The bamboo sleeper base (1) is obtained by first pressing the radial bamboo strip unit (11) to a preset pressure, then heating it to a preset temperature and curing it for a preset time.
5. The three-dimensional protective bamboo composite sleeper according to claim 4, characterized in that: The preset temperature is 100℃~165℃.
6. The three-dimensional protective bamboo composite sleeper according to claim 4, characterized in that: The preset pressure is 10MPa to 30MPa.
7. The three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: The protective layer (2) and the protective body (14) may be made of the same or different materials; When the materials are the same, the protective layer (2) and the protective body (14) are protective coating structures formed by immersing the bamboo sleeper base (1) in the protective coating for a predetermined time; When the materials are different, the protective layer (2) and the protective body (14) are a step-by-step integral structure formed by first filling the gap (12) with the protective body (14) and then wrapping the protective layer (2) around the bamboo rail sleeper base (1).
8. The three-dimensional protective bamboo composite sleeper according to any one of claims 1 to 7, characterized in that: The upper part of the bamboo track sleeper base (1) is provided with a support part (3) for supporting the fixed track.
9. The three-dimensional protective bamboo composite sleeper according to any one of claims 1 to 7, characterized in that: The radial bamboo strip units (11) are arranged in a disordered manner, so that the protective body (14) forms a three-dimensional mesh structure.
10. The three-dimensional protective bamboo composite sleeper according to any one of claims 1 to 7, characterized in that: The bamboo sleeper base (1) is rectangular in shape, and the radial bamboo strip units (11) are arranged longitudinally.
11. A method for manufacturing a three-dimensional protective bamboo composite railway sleeper, characterized in that: Includes the following steps: S1. The original bamboo, which retains the green and yellow parts, is radially split and dried to obtain radial bamboo strip units (11). S2. The radial bamboo strip unit (11) is immersed in an adhesive with a solid content of 28% to 60% without being rubbed or pressed. After the adhesive is applied, it is dried until the moisture content of the radial bamboo strip unit (11) is 8% to 20%. After obtaining the adhesive, the radial bamboo strip unit (11) is dried. S3. The dried radial bamboo strip units (11) after gluing are assembled in the mold, and pressure is applied to press the dried radial bamboo strip units (11) together to obtain a pressed blank. S4. The pressed blank is cured at a temperature of 100-165℃. After curing, the mold is removed to obtain the bamboo rail sleeper blank. There are gaps (12) between the radial bamboo strip units (11) inside the bamboo rail sleeper blank. S5. Process the bamboo sleeper blank into the target size and shape to obtain the bamboo sleeper base (1); S6. The bamboo sleeper base (1) is directly subjected to protective treatment without scoring, resulting in a three-dimensional protective bamboo composite sleeper. The surface of the bamboo sleeper base (1) has a protective layer (2) formed by protective coating, and the gap (12) inside the bamboo sleeper base (1) has a protective body (14) formed by protective coating.
12. The manufacturing method of the three-dimensional protective bamboo composite sleeper according to claim 11, characterized in that: In step S1, the thickness of the radial bamboo strip unit (11) is 0.5mm to 3mm and the width is 3mm to 12mm.
13. The manufacturing method of the three-dimensional protective bamboo composite railway sleeper according to claim 11, characterized in that: In step S2, the adhesive is one or more of the following: phenolic resin, isocyanate, polyurethane, resorcinol, and urea-formaldehyde resin, with a solid content of 28% to 60%.
14. The manufacturing method of the three-dimensional protective bamboo composite sleeper according to claim 11, characterized in that: In step S3, the pressure in the pressurization step is 10MPa to 30MPa.
15. The manufacturing method of the three-dimensional protective bamboo composite railway sleeper according to claim 11, characterized in that: In step S4, the curing time is 2h to 12h.
16. The manufacturing method of the three-dimensional protective bamboo composite railway sleeper according to claim 11, characterized in that: In step S5, the target dimensions are a length of 2000mm to 5000mm, a width of 200mm to 300mm, and a thickness of 130mm to 300mm.
17. The manufacturing method of the three-dimensional protective bamboo composite railway sleeper according to claim 11, characterized in that: In step S6, the protective treatment includes the following steps: coating the surface of the bamboo sleeper substrate (1) with a protective coating and penetrating into the internal gaps (12) of the bamboo sleeper substrate (1); the protective coating is one or more of polyurea coating, styrene-acrylic coating, silicone-acrylic coating, etc.
18. The manufacturing method of the three-dimensional protective bamboo composite sleeper according to claim 17, characterized in that: In step S6, the protection process is at least one of feature A to feature C: A. Immerse the bamboo sleeper base (1) in a protective coating under normal pressure; B. The bamboo sleeper base (1) is impregnated with protective coating under pressure; C. Apply protective coating to the bamboo sleeper substrate (1).
19. The manufacturing method of the three-dimensional protective bamboo composite railway sleeper according to claim 17, characterized in that: In step S6, the protective layer (2) on the surface of the bamboo sleeper base (1) and the protective body (14) in the gap (12) inside the bamboo sleeper base (1) are integrally formed to form a three-dimensional network protective structure.