Three-dimensional protection bamboo composite sleeper and manufacturing method thereof

Abstract

The invention discloses a three-dimensional protective bamboo composite sleeper and a manufacturing method thereof. The manufacturing method comprises the steps that S1, raw bamboos are processed into radial bamboo skin units; s2, the radial bamboo skin units which are not subjected to rolling or rolling treatment are subjected to glue applying treatment, and after glue draining, the radial bamboo skin units are dried to obtain glue; s3, the glued and dried radial bamboo skin units are assembled and pressed, and a pressed blank is obtained; s4, the pressed blank is cured, and a bamboo sleeper blank is obtained; s5, the bamboo sleeper blank is machined into the target size and shape, and a bamboo sleeper base body is obtained; and S6, the bamboo sleeper base body is directly subjected to protection treatment without nicking treatment, and the three-dimensional protection bamboo composite sleeper is obtained. The radial bamboo skin units which are not subjected to rolling or rolling treatment are used as raw materials, gaps are formed between the radial bamboo skin units during assembly and pressing, protective paint can permeate conveniently, the protection durability is improved, the cost is reduced, protection treatment is not needed after special nicking treatment, and the manufacturing process is simpler.

Description

Technical Field

[0001] The 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 a manufacturing method thereof. Background Art

[0002] At present, ballasted tracks in railways and urban rail transit mostly use wooden sleepers, concrete sleepers, steel sleepers, composite sleepers, etc. Except for wooden sleepers, which need to be treated with surface notching due to anti-corrosion and oiling, other sleepers have better surface flatness due to processing technology and aesthetics, and will not be deliberately made into rough surfaces. Wooden sleepers need to be notched on the surface with special notching equipment for anti-corrosion treatment and oiling, which has complex operation process, high notching cost, and limited notching depth.

[0003] Bamboo is an important forest resource in my country. It has excellent physical and mechanical properties and a wide range of applications. In addition, bamboo has a short growth cycle and can be used as timber in 3 to 5 years. In the prior art, there are technical solutions for making bamboo sleepers from bamboo. For example, Chinese patent application No. CN201910063367.0 discloses a one-time integrally formed bamboo sleeper and a preparation method thereof. 1) The pretreated bamboo unit is dried and modified using steam with an overheating degree of 10 to 80 degrees until the moisture content of the bamboo unit is 8 to 20%, thereby obtaining a dried and modified bamboo unit; the pretreatment in step 1) is specifically as follows: removing the green and yellow bamboo units from the bamboo units, steaming and softening them, washing them with water and then rolling and rubbing them to obtain the pretreated bamboo units; 2) dipping the dried and modified bamboo units in step 1) into an adhesive for dipping, spinning, and leaching Dry until the moisture content of the bamboo unit 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 dipping treatment is an ultrasonic pulsation-assisted normal pressure treatment, and the pressure during the dipping treatment is 0.2 to 0.8 MPa; 3) the blank in step 2) is cured and formed at a temperature of 120 to 160° C. to obtain a bamboo sleeper blank; 4) the surface of the bamboo sleeper blank in step 3) is coated with a dopamine solution, and then subjected to a mildew and / or anti-corrosion and / or anti-insect treatment to obtain a bamboo sleeper; the mildew and / or anti-corrosion and / or anti-insect treatment is specifically as follows: the surface of the bamboo sleeper blank is coated with a dopamine solution and then dried, first coated with a titanium sulfate solution, dried, and then coated with a silver nitrate solution, dried to obtain a bamboo sleeper; 5) the bamboo sleeper in step 4) is firmly locked with a fastener to obtain a one-time integrally formed bamboo sleeper. The applicant found that the following technical problems exist in this technical solution: ① The green and yellow colors of the bamboo units are removed, resulting in low material utilization, high cost, and difficulty in large-scale promotion and application; ② The protective treatment process is too complicated and costly, and bamboo filaments are used as bamboo units, which are rolled and rubbed before being dipped in glue and solidified. The rolling of the bamboo filaments will destroy the strength of the bamboo fibers themselves. After rolling and pressing, there are basically no gaps (or grooves) inside the bamboo sleeper blanks. In the subsequent protective treatment process, the protective liquid is difficult to penetrate, combine, and wrap around the bamboo sleepers, which will cause the protection of the bamboo sleepers to fail after a period of use. Therefore, the existing bamboo sleepers still have technical problems such as damaged raw material strength, poor long-term protection effect, low strength, and high cost, which limit the promotion of bamboo sleepers in comprehensive industrial applications. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a three-dimensional protective bamboo composite sleeper with long-lasting protective effect and high strength suitable for ballasted tracks of railways and urban rail transit and a manufacturing method thereof.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for manufacturing a three-dimensional protective bamboo composite sleeper comprises the following steps: S1, radially splitting and drying the original bamboo with green and yellow bamboo strips to obtain radial bamboo strip units; S2, without rolling or pressing, immersing the radial bamboo strips unit in an adhesive with a solid content of 28% to 60% for sizing, drying the radial bamboo strips unit until the moisture content is 8% to 20% after leaching, and drying the radial bamboo strips unit after obtaining the glue; S3, assembling the glue-dried radial bamboo strips units in a mold, and applying pressure to make the glue-dried radial bamboo strips units tightly fit together to obtain a compacted blank; S4, curing the compacted blank at a temperature of 100-165° C., removing the mold after curing to obtain a bamboo sleeper blank, wherein there are gaps between radial bamboo strip units inside the bamboo sleeper blank; S5, processing the bamboo sleeper blank into a target size and shape to obtain a bamboo sleeper matrix; S6. Directly subjecting the bamboo sleeper substrate to protective treatment without scoring to obtain a three-dimensional protective bamboo composite sleeper, wherein the surface of the bamboo sleeper substrate has a protective layer formed by a protective coating and the gap inside the bamboo sleeper substrate has a protective body formed by the protective coating.

[0006] As a further improvement to the above technical solution: In the step S1, the radial bamboo strips unit has a thickness of 0.5 mm to 3 mm and a width of 3 mm to 12 mm.

[0007] Preferably, the thickness of the radial bamboo strips unit is 0.5 mm to 2 mm.

[0008] In the 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%.

[0009] Preferably, when the adhesive is a phenolic resin, the solid content of the phenolic resin is 29% to 55%.

[0010] In the step S3, the pressure in the pressurizing step is 10 MPa to 30 MPa.

[0011] In the step S4, during the curing process, the curing time is 2 hours to 12 hours.

[0012] In step S5, the target dimensions are 2000 mm to 5000 mm in length, 200 mm to 300 mm in width, and 130 mm to 300 mm in thickness.

[0013] In step S6, the protective treatment includes the following steps: coating the surface of the bamboo sleeper substrate with a protective coating and penetrating the protective coating into the internal gap of the bamboo sleeper substrate; the protective coating is one or more of polyurea coating, styrene acrylic coating, silicone acrylic coating, etc.

[0014] In step S6, the protection process is at least one of features A to C: A. Soak the bamboo sleeper substrate in the protective coating at normal pressure; B. Pressurize and immerse the bamboo sleeper substrate in the protective coating; C. Apply protective coating on the bamboo sleeper substrate.

[0015] Preferably, in certain embodiments of the present invention, the protective treatment is performed in multiple steps, such as first immersing the bamboo sleeper substrate in the protective coating at normal pressure or under pressure, and then coating the protective coating on the bamboo sleeper substrate after drying.

[0016] In certain embodiments of the present invention, the protective coating is difficult to penetrate into the internal gaps of the bamboo sleeper substrate with a single coating, and needs to be coated on the bamboo sleeper substrate multiple times, so that the protective coating can easily penetrate into the internal gaps of the bamboo sleeper substrate.

[0017] In step S6, the protective layer on the surface of the bamboo sleeper substrate and the protective body in the internal gap of the bamboo sleeper substrate are integrally formed to form a three-dimensional network protective structure.

[0018] In certain embodiments of the present invention, some gaps inside the bamboo sleeper matrix are filled with protective coating. Preferably, all gaps inside the bamboo sleeper matrix are filled with protective coating.

[0019] As a general inventive concept, the present invention also provides a three-dimensional protective bamboo composite sleeper, which is manufactured by the above-mentioned three-dimensional protective bamboo composite sleeper manufacturing method.

[0020] The step S1 and step S2 also include carbonizing the radial bamboo strips unit, wherein the carbonization temperature is 120-140° C. and the time is 1-3 hours.

[0021] Compared with the prior art, the advantages of the present invention are: The invention discloses a method for preparing a three-dimensional protective bamboo composite sleeper, wherein 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, so that the strength of the bamboo material itself can be retained to the greatest extent, and the maximum resource utilization rate of bamboo material resources can be achieved, and the utilization rate of the original bamboo can be increased from 30% to more than 90%, thereby avoiding the rolling of bamboo filaments to destroy the fiber strength during the processing of ordinary recombinant bamboo. Compared with bamboo bundle unit bamboo sleepers pressed from ordinary bamboo filaments, the radial bamboo strip units have greater mechanical strength, lower price, and simpler operation process. On the other hand, when the radial bamboo strips unit that has not been rubbed or rolled is pressed, since the radial bamboo strips unit has not been rolled, a single radial bamboo strips unit is not easily compressed during assembly and pressing, and the radial bamboo strips units will not fit as tightly and densely as the rolled bamboo silk units. During pressing, gaps (or grooves) can be formed between the radial bamboo strips units, which facilitates the deep combination, filling, penetration and wrapping of the protective coating and the bamboo material during the later protective treatment, enhances the adhesion and bonding force, and achieves a long-term and reliable protective effect. There is no need to deliberately score and then protect, which has an important role in promoting the comprehensive application and promotion of bamboo strips units and bamboo materials in bamboo sleepers. Therefore, the composite bamboo sleeper of the present invention can greatly reduce the price of existing reconstructed bamboo sleepers while improving the strength, avoiding the inability to promote and apply bamboo sleepers on a large scale due to price issues, and has an important role in promoting the comprehensive application and promotion of bamboo sleepers. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a process flow chart of the present invention.

[0023] Figure 2 This is a photo of the radial bamboo strips unit in Example 1 of the present invention.

[0024] Figure 3 It is a schematic diagram of the three-dimensional structure of the three-dimensional protective bamboo composite sleeper in Example 1 of the present invention.

[0025] Figure 4 yes Figure 3 Schematic diagram of the cross-sectional structure of AA.

[0026] Figure 5 yes Figure 4 Enlarged view of point B in the middle.

[0027] Figure 6 It is a schematic diagram of the three-dimensional structure of a bamboo sleeper matrix of a three-dimensional protective bamboo composite sleeper.

[0028] Figure 7 It is a side view structural schematic diagram of a bamboo sleeper base of a three-dimensional protective bamboo composite sleeper.

[0029] Figure 8 It is a structural schematic diagram of another embodiment of a three-dimensional protective bamboo composite sleeper.

[0030] Fig. 9 This is a physical picture of the bamboo sleeper base of the three-dimensional protective bamboo composite sleeper.

[0031] Fig.10 This is a photograph of the bamboo bundle unit used in Comparative Example 1 of the present invention.

[0032] Legend: 1. Bamboo sleeper base; 11. Radial bamboo strip unit; 12. Gap; 13. Adhesive body; 14. Protective body; 2. Protective layer; 3. Load-bearing part. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Unless otherwise specified, the following materials or instruments and equipment are all commercially available.

[0034] Example 1 Take the manufacturing of bamboo sleepers with a width of 220mm, a thickness of 160mm and a length of 2500mm as an example. Figure 1 As shown, a method for manufacturing a three-dimensional protective bamboo composite sleeper in this embodiment specifically includes the following steps: A 5-year-old bamboo is selected and cut in length, each section being 2500 mm ± 10 mm, to obtain an original bamboo section. The original bamboo section is split into arc-shaped bamboo units with green and yellow bamboo retained, and the arc-shaped bamboo units with green and yellow bamboo retained are processed into radial bamboo strip units 11 with a length of 2500 mm, a width of 10 mm, and a thickness of 1.5 mm by a radial strip splitting machine, as shown in FIG. Figure 2 As shown, Figure 2 (a) is a physical end view of the radial bamboo strip unit 11, Figure 2 (b) is a top view of the radial bamboo strip unit 11. It can be seen from the figure that the radial bamboo strip unit 11 has not been crushed and includes a green bamboo part, a fleshy bamboo part and a yellow bamboo part. The radial bamboo strip unit 11 of this embodiment has not been carbonized. If no protective treatment is performed, the weather resistance performance cannot reach the strong corrosion resistance level I. However, the present invention subsequently performs protective treatment, and the protective coating wraps the bamboo sleeper substrate 1 to isolate the external moisture without affecting the overall weather resistance performance.

[0035] The thickness of the radial bamboo strip unit 11 of the present invention is 0.5mm to 3mm, and the width is 3mm to 12mm, and the same or similar technical effects can be obtained. Within the 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 gluing surface, and the gluing area of ​​the bamboo green part and the bamboo yellow part is small, so gluing can be achieved without rolling into bamboo bundle units, and the impact on the gluing performance is relatively small.

[0036] The radial bamboo strips unit 11 is dried with 100°C hot air to a moisture content of about 10%. The radial bamboo strips unit 11 after drying is soaked in a phenolic resin with a solid content of 29% at normal pressure for 20 minutes to absorb glue, and the glue solution is kept flowing during soaking to ensure the uniformity of the glue solution. After soaking, the excess adhesive is drained off, and then dried at 60°C until the moisture content of the radial bamboo strips unit 11 is 8% to 20%, and the radial bamboo strips unit 11 is dried after glue is obtained. In other embodiments, the sizing treatment can be treated at a pressure of 0.2 to 0.8 MPa for 10 to 15 minutes, and the same or similar technical effects can also be achieved.

[0037] The dried radial bamboo strips unit 11 after gluing is assembled in a mold of matching size and pressurized at a pressure of 25 MPa to fully press and fit the bamboo strips unit to ensure the subsequent curing and gluing of the adhesive. The pressure of the present invention is 10 to 30 MPa. When the pressure is too small, such as 5 MPa, the radial bamboo strips unit 11 is not tightly fitted and the gluing performance is poor. In severe cases, it fails to be pressed and formed, and even the board will be scattered (the radial bamboo strips unit 11 is scattered and cannot be glued together). If the pressure is too large, such as 40 MPa, the radial bamboo strips unit 11 is too tightly fitted, and the internal gap 12 is too small, which affects the deep penetration of the protective coating in the subsequent steps, and ultimately affects the three-dimensional protective effect. Since the present invention needs to leave a gap 12 (or groove) between the radial bamboo strips unit 11 to facilitate the penetration of the protective coating into the interior of the bamboo sleeper matrix 1, there is no requirement for sorting and aligning the radial bamboo strips unit 11 during assembly, and the radial bamboo strips unit 11 is arranged in disorder.

[0038] The blank pressed by the mold is cured at 150°C for 4 hours. After the curing is completed, the mold is removed to obtain the bamboo sleeper blank. The bamboo sleeper blank is first machined in terms of length, width and thickness. The bamboo sleeper in this embodiment is sized to be 2500mm long, 220mm wide and 160mm thick. It is then shaped and drilled to obtain the bamboo sleeper base 1. The drilling process is to open fixing bolt holes on the bamboo sleeper for easy installation of the rails. The product in this embodiment is shaped like an ordinary cuboid and the surface does not need to be separately notched. The diameter of the fixing bolt hole is 22mm in diameter to meet the sleeper usage size, appearance and installation requirements.

[0039] The machined bamboo sleeper substrate 1 is treated with a highly waterproof, weather-resistant and elastic polyurea coating (commercially available) by soaking it at normal pressure to penetrate, combine and wrap it to form an integrated protective layer for overall protection. All-round treatment is required to obtain a three-dimensional protective bamboo composite sleeper, such as Figure 3 , Figure 6 and Fig. 9The manufacturing method of the three-dimensional protective bamboo composite rail sleeper of the present invention processes the original bamboo with green and yellow bamboo into radial bamboo strip units 11, reorganizes and utilizes the radial bamboo strips that do not need to be removed from the green and yellow, and naturally forms gaps 12 (or grooves) between the radial bamboo strip units 11 when the radial bamboo strip units 11 that are not rolled are solidified and pressed, which facilitates the combination, filling, penetration and wrapping of the protective coating and the bamboo material during the subsequent protective treatment, enhances the adhesion and bonding force, and achieves a long-term and reliable protective effect. There is no need to deliberately add a process for scoring to allow the protective coating to penetrate, which can simplify the process and reduce the processing cost while improving the protective treatment effect.

[0040] In the present invention, since the radial bamboo strip units 11 are not rolled, a single radial bamboo strip unit 11 is not easily compressed during assembly and pressing, and the radial bamboo strip units 11 are not directly fitted tightly and densely like rolled bamboo silk units. Therefore, when the adhesive is pressed into a three-dimensional protective bamboo composite sleeper to bond the surface of the radial bamboo strip units 11, gaps 12 (or grooves) can be formed inside the radial bamboo strip units 11, and the gaps 12 (or grooves) are not completely filled with the adhesive. During subsequent protective treatment, the protective coating can penetrate into the gaps 12 (or grooves) inside the pressed bamboo sleeper substrate 1, and the gaps 12 (or grooves) are filled, infiltrated, combined and wrapped with the protective coating. However, the fiber structure of the existing rolled bamboo bundle units is destroyed, and they are easily compressed and tightly fitted during pressing. Basically, no gaps 12 (or grooves) are formed between the bamboo bundle units, and there are no objective conditions for filling the inside of the bamboo sleeper matrix 1 with penetrating protective coating. The unrolled radial bamboo strips unit 11 of the present invention and the existing rolled bamboo bundle units have two different structures after pressing. The existence of the internal gaps 12 (or grooves) makes it easier for the protective coating to penetrate deeply and build a three-dimensional network protection structure.

[0041] In other embodiments, the protective treatment is carried out under conditions of pressurized impregnation at a pressure of 0.6 to 1.2 MPa, which can be completed in a shorter time (15 to 20 minutes for normal pressure immersion and only 5 to 10 minutes for pressurized impregnation), and the same or similar technical effects can be achieved.

[0042] In the present embodiment, radial bamboo strips with bamboo green and bamboo yellow retained are used to manufacture three-dimensional protective bamboo composite sleepers through coupling of multiple technologies such as gluing, drying after gluing, pressing, heat curing, machining, and surface protection treatment. The specific process flow of the present embodiment is as follows: cutting of original bamboo → breaking of original bamboo segments → radial strip splitting → drying of radial bamboo strip units 11 → phenolic glue dipping → drying after gluing → assembly → pressing → heat curing → machining → surface integrated protection treatment → three-dimensional protective bamboo composite sleepers.

[0043] like Figures 3 to 9As shown, 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 a plurality of radial bamboo strip units 11 that have not been subjected to rolling or compacting treatment and a plurality of gaps 12, each radial bamboo strip unit 11 is wrapped with an adhesive 13, each radial bamboo strip unit 11 is bonded by the adhesive 13, the gap 12 is formed between at least two radial bamboo strip units 11, the gap 12 is filled with a protective body 14, and the protective body 14 is connected to the protective layer 2 as a whole.

[0044] The three-dimensional protective bamboo composite sleeper of the present invention has the following characteristics: first, the surface of the radial bamboo strip units 11 has not been subjected to rubbing or rolling treatment, which does not damage the strength of the bamboo fiber itself and is conducive to the penetration 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 a plurality of gaps 12, the gaps 12 are formed between at least two radial bamboo strip units 11, the gaps 12 are filled with protective bodies 14, and the protective bodies 14 are connected to the protective layer 2 as a whole, so that the protective body 14 in the bamboo sleeper base 1 is combined with the protective layer 2 wrapped outside the bamboo sleeper base 1, forming a three-dimensional protective effect, the protective layer 2 is not easy to fall off, the protective time is long, and the overall strength is high.

[0045] Furthermore, in this embodiment, the adhesive body 13 on the surface of the radial bamboo strip unit 11 is formed by soaking the radial bamboo strip unit 11 in an adhesive for a preset time, drying it, and then pressing and curing it, which is beneficial to improve the overall bonding strength. Preferably, the adhesive body 13 is a phenolic resin body, which has good bonding effect and good weather resistance, and is beneficial to improve the overall bonding strength.

[0046] Furthermore, if Figure 6 , Figure 7 , Fig. 9 As shown, in this embodiment, the bamboo sleeper base 1 is obtained by first pressurizing the assembled radial bamboo strips 11 to a preset pressure, then heating to a preset temperature and curing for a preset time, which is convenient to process and has high production efficiency. Further, the preset temperature is 100°C to 165°C, and the preset pressure is 10MPa to 30Mpa.

[0047] In other embodiments of the present invention, the materials of the protective layer 2 and the protective body 14 are the same or different; 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 the protective coating for a predetermined time; when the materials are different, the protective layer 2 and the protective body 14 are step-molded integrated structures formed by first filling the gap 12 with the protective body 14 and then wrapping the protective layer 2 outside the bamboo sleeper substrate 1. Preferably, the material of the protective layer 2 and the protective body 14 is 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 the polyurea coating for a predetermined time. The protective layer 2 and the protective body 14 are formed at one time by immersing the bamboo sleeper substrate 1 in the polyurea coating for a predetermined time, which is convenient to produce and has a good long-lasting protective effect.

[0048] Furthermore, in this embodiment, the radial bamboo strip units 11 are arranged in a disordered manner, so that the protective body 14 forms a three-dimensional network structure, further improving the protective effect.

[0049] Furthermore, in this embodiment, the bamboo sleeper base 1 is in a rectangular parallelepiped shape, and the radial bamboo strip units 11 can be arranged longitudinally.

[0050] In some embodiments of the present invention, a bearing portion 3 for bearing and fixing the rail is provided on the upper portion of the bamboo sleeper base 1. Figure 8 The bearing portion 3 is provided with threaded holes for fixing the rails by bolts.

[0051] Example 2 Taking the manufacture of bamboo sleepers with a width of 220 mm, a thickness of 160 mm, and a length of 2500 mm as an example, a method for manufacturing a three-dimensional protective bamboo composite sleeper in this embodiment specifically includes the following steps: (1) Select 5-year-old bamboo and cut it in length, with each section being 2500 mm + 10 mm to obtain the original bamboo sections.

[0052] (2) The original bamboo segment is split into arc-shaped bamboo units with green and yellow bamboo retained, and then the arc-shaped bamboo units with green and yellow bamboo retained are processed into radial bamboo strip units 11 with a length of 2500 mm, a width of 10 mm, and a thickness of 1.5 mm by a radial strip splitting machine.

[0053] (3) The radial bamboo strip unit 11 is carbonized at 130° C. for 2 h to further improve the anti-corrosion and anti-mildew performance, so that the anti-corrosion performance reaches the strong corrosion resistance level I.

[0054] (4) The radial bamboo strips unit 11 is dried with hot air at 100° C. to a moisture content of about 10%.

[0055] (5) The radial bamboo strips unit 11 after drying is immersed in a phenolic resin with a solid content of 29% at normal pressure for 20 minutes to absorb glue. During the immersion, the glue solution is kept flowing to ensure the uniformity of the glue solution. After the immersion, the excess adhesive is drained off, and then the radial bamboo strips unit 11 is dried at 60° C. until the moisture content of the radial bamboo strips unit 11 is 8% to 20%. After obtaining the glue, the radial bamboo strips unit 11 is dried.

[0056] (6) The dried radial bamboo strips unit 11 after gluing is assembled in a mold with matching size and pressurized at a pressure of 25 MPa to ensure that the bamboo strips unit is fully pressed and fitted to ensure the subsequent curing and gluing of the adhesive.

[0057] (7) The blank pressed by the mold is cured at 150°C for 4 h. After the curing is completed, the mold is removed to obtain a bamboo sleeper blank.

[0058] (8) The bamboo sleeper blank is first machined to the desired length, width and thickness. The bamboo sleeper in this embodiment is machined to have a length of 2500 mm, a width of 220 mm and a thickness of 160 mm. The blank is then shaped and drilled to obtain a bamboo sleeper base 1. The drilling process is to open holes for fixing bolts on the bamboo sleeper for installing rails.

[0059] The shape of this embodiment is a common rectangular parallelepiped and the surface does not need to be separately notched. The diameter of the hole drilled for the fixing bolt is 22 mm in diameter to meet the use size, appearance and installation requirements of the sleeper.

[0060] (9) The machined bamboo sleeper substrate 1 is subjected to overall protection treatment by using a highly waterproof, highly weather-resistant and highly elastic polyurea coating to penetrate, combine and wrap the substrate through pressurized impregnation to form an integrated protective layer. The treatment is carried out for 10 minutes at a pressure of 0.6 MPa to further increase the penetration depth of the protection treatment and ensure that the treatment is carried out in all directions, thereby obtaining a three-dimensional protective bamboo composite sleeper.

[0061] In the present embodiment, radial bamboo strips with bamboo green and bamboo yellow retained are used to manufacture three-dimensional protective bamboo composite sleepers through the coupling of multiple technologies such as carbonization, drying, gluing, drying after gluing, pressing, heat curing, machining, and surface protection treatment. The specific process flow of the present embodiment is as follows: cutting of original bamboo → breaking of original bamboo segments → radial strip splitting → carbonization of radial bamboo strip units 11 → drying of radial bamboo strip units 11 → phenolic glue dipping → drying after gluing → assembly → pressing → heat curing → machining → surface integrated protection treatment → three-dimensional protective bamboo composite sleepers.

[0062] Example 3 Taking the manufacture of bamboo sleepers with a width of 220 mm, a thickness of 160 mm, and a length of 2500 mm as an example, a method for manufacturing a three-dimensional protective bamboo composite sleeper in this embodiment specifically includes the following steps: (1) Select 5-year-old bamboo and cut it in length, with each section being 2500 mm + 10 mm to obtain the original bamboo sections.

[0063] (2) The original bamboo segment is split into arc-shaped bamboo units with green and yellow bamboo retained, and then the arc-shaped bamboo units with green and yellow bamboo retained are processed into radial bamboo strip units 11 with a length of 2500 mm, a width of 10 mm, and a thickness of 1.2 mm by a radial strip splitting machine.

[0064] (3) The radial bamboo strips unit 11 is carbonized at 130°C for 2h to further improve the anti-corrosion and anti-mildew performance, so that the 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 manufactured by the carbonized radial bamboo strips unit 11 will be better than the bamboo composite sleeper manufactured by the uncarbonized radial bamboo strips unit 11 in Example 1.

[0065] (4) The radial bamboo strips unit 11 is dried with hot air at 100° C. to a moisture content of about 10%.

[0066] (5) The radial bamboo strips unit 11 after drying is immersed in a conventional commercially available modified isocyanate adhesive (produced by Taier Adhesive (Guangdong) Co., Ltd.) with a solid content of 35% at normal pressure for 20 minutes to absorb the adhesive. During the immersion, the adhesive solution is kept flowing to ensure the uniformity of the adhesive solution. After the immersion, the excess adhesive is drained off, and then the radial bamboo strips unit 11 is dried at 60° C. until the moisture content of the radial bamboo strips unit 11 is 8% to 20%. After obtaining the adhesive, the radial bamboo strips unit 11 is dried.

[0067] (6) The dried radial bamboo strips unit 11 after gluing is assembled in a mold with matching size and pressurized at a pressure of 25 MPa to fully press and fit the bamboo strips unit to ensure the subsequent curing and gluing of the adhesive, thereby obtaining a compact blank.

[0068] (7) The blank pressed by the mold is cured at 130°C for 10 h. After the curing is completed, the mold is removed to obtain a bamboo sleeper blank.

[0069] (8) The bamboo sleeper blank is first machined into the dimensions of length, width and thickness. The bamboo sleeper in this embodiment is machined into the dimensions of 2500 mm in length, 220 mm in width and 160 mm in thickness. Then, the blank is shaped and drilled to obtain a bamboo sleeper base 1.

[0070] The shape of this embodiment is a common rectangular parallelepiped and the surface does not need to be separately notched. The diameter of the hole drilled for the fixing bolt is 22 mm in diameter to meet the use size, appearance and installation requirements of the sleeper.

[0071] (9) The machined bamboo sleeper substrate 1 is subjected to overall protection treatment by using a highly waterproof, highly weather-resistant and highly elastic polyurea coating to penetrate, combine and wrap the substrate through pressurized impregnation to form an integrated protective layer. The treatment is carried out for 10 minutes at a pressure of 0.6 MPa to further increase the penetration depth of the protection treatment and ensure that the treatment is carried out in all directions, thereby obtaining a three-dimensional protective bamboo composite sleeper.

[0072] In this embodiment, radial bamboo strips that retain bamboo green and bamboo yellow are used to manufacture three-dimensional protective bamboo composite sleepers through the coupling of multiple technologies such as carbonization, drying, gluing, post-gluing drying, pressing, heat curing, machining, and surface protection treatment.

[0073] The specific process flow of this embodiment is as follows: cutting of original bamboo → breaking of original bamboo segments → radial splitting → carbonization of radial bamboo strip units 11 → drying of radial bamboo strip units 11 → dipping in modified isocyanate adhesive → drying after gluing → assembly → pressing → heat curing → machining → surface integrated protection treatment → three-dimensional protective bamboo composite sleeper.

[0074] Example 4 The manufacturing method of this embodiment is the same as that of embodiment 1, except that in step (8) of this embodiment, a highly waterproof, highly weather-resistant and highly elastic polyurea coating (commercially available) is applied multiple times (twice in this embodiment) to the machined bamboo sleeper substrate 1 to penetrate, combine and wrap the substrate to form an integrated protective layer for overall protection.

[0075] The anti-corrosion and anti-mildew performance of the composite bamboo sleeper product of this embodiment is the same as that of embodiment 1, which is the highest level. However, after the protective layer 2 on the surface of the product is destroyed, since embodiment 4 only performs protective treatment by coating, it is difficult for the protective coating to penetrate deeply into the gap 12 in the core of the bamboo sleeper substrate 1. When the surface protective layer 2 of the products of embodiment 1 and embodiment 4 is destroyed to the same extent, the anti-corrosion, anti-mildew and waterproof performance of the product in embodiment 4 is inferior to that of embodiment 1, indicating that compared with protective treatment by coating, protective treatment by pressurized impregnation and normal pressure immersion is more conducive to the deep penetration of the protective coating of the bamboo sleeper substrate 1 into the bamboo sleeper substrate 1, and the protection is more durable.

[0076] Comparative Example 1 Taking the manufacture of bamboo sleepers with a width of 220 mm, a thickness of 160 mm, and a length of 2500 mm as an example, the manufacturing method of the rolled bamboo bundle recombined bamboo three-dimensional protective bamboo composite sleeper of this comparative example specifically comprises the following steps: (1) Select 5-year-old bamboo and cut it in length, with each section being 2500 mm + 10 mm to obtain the original bamboo sections.

[0077] (2) The original bamboo segment is split into arc-shaped bamboo units with green and yellow bamboo retained, the green and yellow bamboo on the surface of the arc-shaped bamboo unit is removed, and then the arc-shaped bamboo unit is rolled into a bamboo bundle unit with a length of 2500 mm, a width of 30 mm, and a thickness of 6.5 mm, such as Fig.10 shown. Fig.10 (a) is the end view of the bamboo bundle unit after rolling. Fig.10 (b) is a top view of the bamboo bundle unit after rolling, which shows that the inside and surface of the bamboo bundle unit are cracked and decomposed, and it does not have the strength of the bamboo unit that has not been rolled.

[0078] (3) The above-mentioned bamboo bundle unit is carbonized at 130°C for 2 hours to further improve the anti-corrosion and anti-mildew properties, so that the anti-corrosion performance reaches the strong corrosion resistance level I.

[0079] (4) The bamboo bundle unit is dried with hot air at 100° C. until the moisture content is about 10%.

[0080] (5) Soaking the dried bamboo bundle unit in a phenolic resin with a solid content of 25% at normal pressure for 20 minutes to absorb glue. During the soaking, the glue solution is kept flowing to ensure the uniformity of the glue solution. After the soaking, the excess adhesive is drained off, and then the radial bamboo strip unit 11 is dried at 60° C. until the moisture content of the radial bamboo strip unit 11 is 8% to 20%. After obtaining the glue, the radial bamboo strip unit 11 is dried.

[0081] In other embodiments, the sizing treatment may be carried out at a pressure of 0.2 to 0.8 MPa for 10 to 15 minutes, which may also achieve the same or similar technical effects.

[0082] (6) The glued and dried bamboo bundle units are assembled in a mold of matching size and pressurized with a pressure of 25 MPa to ensure that the bamboo bundle units are fully pressed and fitted to ensure the subsequent curing and bonding of the adhesive.

[0083] (7) The blank pressed by the mold is cured at 150°C for 4 h. After the curing is completed, the mold is removed to obtain a bamboo sleeper blank.

[0084] (8) The bamboo sleeper blank is first machined to the desired length, width and thickness. The bamboo sleeper in this embodiment is machined to have a length of 2500 mm, a width of 220 mm and a thickness of 160 mm. The blank is then shaped and drilled to obtain a bamboo sleeper base 1. The drilling process is to open holes for fixing bolts on the bamboo sleeper base 1 for installing rails.

[0085] The shape of this comparative example is a common rectangular parallelepiped, and the diameter of the hole for the fixing bolt is 22mm in diameter, so as to meet the use size, appearance and installation requirements of the sleeper.

[0086] (9) The machined bamboo sleeper substrate 1 is notched on the four surfaces of top, bottom, left and right using a notching machine, and the notching depth is generally about 10 mm.

[0087] (10) The bamboo sleeper substrate 1 that has been machined and scored is subjected to overall protective treatment by infiltrating, combining, and wrapping with a highly waterproof, weather-resistant, and elastic polyurea coating through pressurized impregnation to form an integrated protective layer. The treatment is carried out at a pressure of 0.6 MPa for 10 minutes to further increase the penetration depth of the protective treatment and ensure that all-round treatment is in place, thereby obtaining a bamboo composite sleeper with three-dimensional protection of bamboo bundle units.

[0088] The specific steps of this comparative example are as follows: cutting of original bamboo → breaking of original bamboo segments → removing green and yellow from arc-shaped bamboo units → rolling of bamboo bundle units → carbonization of bamboo bundle units → drying of bamboo bundle units → phenolic glue dipping → drying after gluing → assembly → pressing → heat curing → machining → surface notching treatment → surface integrated protection treatment → three-dimensional protection of bamboo bundle units for bamboo composite sleepers.

[0089] In this comparative example, the bamboo bundle units need to be de-greened and de-yellowed, and the material utilization rate is low. In addition, the rolling of bamboo filaments will destroy the strength of bamboo fibers themselves. When the bamboo bundles are pressed together, the bamboo bundle units inside the sleeper are tightly connected with basically no gap 12. Therefore, it is difficult to penetrate, combine, and wrap during the final overall protective treatment process. If no special scoring treatment is performed, the integrated protective layer will have a poor bonding effect. Even if the surface is scored to increase some of the protective treatment effects, the protective treatment effect is only on the surface, and the core layer of the bamboo sleeper is not subjected to three-dimensional protective treatment, that is, it is impossible to achieve deep and complete penetration, combination, and wrapping.

[0090] The composite sleepers of Example 1 and Comparative Example 1 were subjected to performance tests, and it was found that the performance of Example 1 was better than that of Comparative Example 1, which is specifically reflected in: ① High strength: the three-dimensional protective bamboo composite sleeper of Example 1 with the same cross-section and thickness (20 mm thick test specimen) is more than 25% higher in bending strength than the bamboo bundle three-dimensional protective bamboo composite sleeper of Comparative Example 1. The product specimens of this embodiment have an average bending strength of 190 MPa and a bending elastic modulus of 15,500 MPa, while the product specimens of the comparative example have an average bending strength of about 150 MPa and a bending elastic modulus of 12,500 MPa; ② Weather resistance: the anti-corrosion and anti-mildew grades are both the highest grades (Grade I and Grade 0), but the method of Example 1 is simpler and more convenient, has lower cost, the integrated protective coating lasts longer, and the water resistance softening coefficient is greater than 0.85. Overall, it has lower cost and better performance.

[0091] Comparative Example 2 The preparation method of a recombinant material in this comparative example is substantially the same as that in Example 2, except that: in step (5) of this comparative example, the adhesive is a 22% phenolic resin adhesive.

[0092] The recombinant material prepared in this comparative example has a 2-hour boiling water water absorption thickness expansion rate test, and the expansion rate exceeds 25%, and some radial bamboo strips units 11 are peeled off from the product, indicating that the bonding performance of the comparative example is poor and does not meet the outdoor performance requirements. The expansion rate of the composite bamboo rail sleeper in Example 2 of the present invention is less than or equal to 8%, and there is no radial bamboo strips unit 11 peeling off from the product, which meets the outdoor performance requirements. The radial bamboo strips unit 11 has poor permeability when the adhesive is not rolled and sucked. If a phenolic resin adhesive with a low solid content (such as 25% and below) is used, the phenolic resin adhesive component under the low solid content condition contains a large amount of water. When sucking glue, the molecular weight of the water molecule is smaller than the molecular weight of the adhesive, and water is preferentially absorbed. After drying, the water evaporates, and the actual effective glue absorption amount of the radial bamboo strips unit 11 is low, which is not conducive to later bonding, and the gluing effect is poor. In severe cases, it fails to be pressed and formed, and even the board will be scattered (the radial bamboo strips unit 11 is scattered and cannot be glued together).

[0093] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for manufacturing a three-dimensional protective bamboo composite sleeper, characterized in that: The following steps are involved: S1, radially splitting and drying the original bamboo with green and yellow bamboo strips to obtain radial bamboo strip units (11); S2, immersing the radial bamboo strip unit (11) in an adhesive having a solid content of 28% to 60% without rolling or pressing, and drying the radial bamboo strip unit (11) until the moisture content of the radial bamboo strip unit (11) is 8% to 20% after the glue is obtained, and drying the radial bamboo strip unit (11); S3, assembling the glue-dried radial bamboo strip units (11) in a mold, and applying pressure to make the glue-dried radial bamboo strip units (11) tightly fit together to obtain a compacted blank; S4, curing the compacted blank at a temperature of 100-165° C., removing the mold after curing, and obtaining a bamboo sleeper blank, wherein gaps (12) exist between radial bamboo strip units (11) inside the bamboo sleeper blank; S5, processing the bamboo sleeper blank into a target size and shape to obtain a bamboo sleeper base (1); S6. The bamboo sleeper substrate (1) is directly subjected to protective treatment without being subjected to notch treatment, so as to obtain a three-dimensional protective bamboo composite sleeper, wherein the surface of the bamboo sleeper substrate (1) has a protective layer (2) formed by a protective coating, and the internal gap (12) of the bamboo sleeper substrate (1) has a protective body (14) formed by the protective coating.

2. The method for manufacturing the three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: In the step S1, the radial bamboo strip unit (11) has a thickness of 0.5 mm to 3 mm and a width of 3 mm to 12 mm.

3. The method for manufacturing the three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: In the 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%.

4. The method for manufacturing the three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: In the step S3, the pressure in the pressurizing step is 10 MPa to 30 MPa.

5. The method for manufacturing the three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: In the step S4, during the curing process, the curing time is 2 hours to 12 hours.

6. The method for manufacturing the three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: In step S5, the target dimensions are 2000 mm to 5000 mm in length, 200 mm to 300 mm in width, and 130 mm to 300 mm in thickness.

7. The method for manufacturing the three-dimensional protective bamboo composite sleeper according to claim 1, characterized in that: In step S6, the protective treatment comprises the following steps: coating the surface of the bamboo sleeper substrate (1) with a protective coating and penetrating the protective coating into the internal gap (12) of the bamboo sleeper substrate (1); the protective coating is one or more of polyurea coating, styrene acrylic coating, silicone acrylic coating, etc.

8. The method for manufacturing the three-dimensional protective bamboo composite sleeper according to claim 7, characterized in that: In step S6, the protection process is at least one of features A to C: A. immersing the bamboo sleeper substrate (1) in a protective coating at normal pressure; B. Dipping the bamboo sleeper substrate (1) into the protective coating under pressure; C. Applying a protective coating on the bamboo sleeper substrate (1).

9. The method for manufacturing the three-dimensional protective bamboo composite sleeper according to claim 7, 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 internal gap (12) of the bamboo sleeper base (1) are integrally formed to form a three-dimensional network protective structure.

10. A three-dimensional protective bamboo composite sleeper, characterized in that: The three-dimensional protective bamboo composite sleeper is manufactured by the manufacturing method of the three-dimensional protective bamboo composite sleeper according to any one of claims 1 to 9.

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