Manufacturing method of high-curvature high-rigidity bamboo compression spring

Abstract

The invention provides a manufacturing method of a high-curvature and high-rigidity bamboo compression spring, which comprises the following steps of: 1, cutting bamboo into bamboo strips, and air-drying and storing the bamboo strips; secondly, the air-dried bamboo canes in the first step are immersed in a sodium hydroxide solution to be subjected to alkali pretreatment, after alkali pretreatment is finished, the bamboo canes are washed with clear water to remove redundant sodium hydroxide solution, finally, natural air drying is conducted at the room temperature, and the pretreated bamboo canes are obtained; and thirdly, the pretreated bamboo strips obtained in the second step are wound in a spiral groove of a cylindrical mold and fixed and shaped through a clamp, and finally the bamboo compression spring is obtained after demolding. According to the method, alkali pretreatment is conducted on the bamboo canes to remove part of lignin and cellulose, the bamboo canes are softened, spiral winding shaping can be conveniently conducted on the bamboo canes, and the bamboo compression spring with the high curvature and the high rigidity can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of compression springs, and particularly relates to a method for manufacturing a high-curvature and high-rigidity bamboo compression spring. Background Art

[0002] Traditional compression spring materials, such as alloy steel and carbon fiber, suffer from high energy consumption during processing and difficulty in recycling. Bamboo compression springs, however, offer advantages such as lightweight and processability, and have been used in fields such as construction and automotive interiors. Existing bamboo springs, with publication number CN204327825 U, are manufactured using heat-softening and bending to form the springs. However, these springs exhibit low curvature and low stiffness. Many applications currently require bamboo compression springs with higher curvature and stiffness. Therefore, the development of bamboo compression springs with higher curvature and stiffness is crucial. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for manufacturing a high-curvature and high-rigidity bamboo compression spring. The high bamboo spring prepared by this manufacturing method has high stiffness and meets the application scenarios of high curvature.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for manufacturing a high-curvature and high-rigidity bamboo compression spring, characterized in that the manufacturing method comprises: Step 1: Cut the bamboo into strips and air-dry them for storage; Step 2: immersing the air-dried bamboo strips in step 1 in a sodium hydroxide solution for alkaline pretreatment, rinsing with clean water to remove excess sodium hydroxide solution after the alkaline pretreatment, and finally air-drying naturally at room temperature to obtain pretreated bamboo strips; Step 3: Wrap the pre-treated bamboo strips obtained in step 2 in the spiral groove of the cylindrical mold and fix it with a clamp to shape it. Finally, demould to obtain a bamboo compression spring with a curvature of 0.02-0.1mm. -1 , stiffness is 0.3-6.5N / mm.

[0005] Preferably, the bamboo strips are rectangular or circular in cross section. The bamboo strips with rectangular cross section have a thickness of 2-5 mm, a length of 200-950 mm, and a width of 10-25 mm. The bamboo strips with circular cross section have a diameter of 3-5 mm and a length of 150-750 mm.

[0006] Preferably, the temperature of the sodium hydroxide solution in step 2 is 35°C-95°C, and the concentration is 5-18wt%. Preferably, the alkali pretreatment time in step 2 is 2-5 hours.

[0007] Preferably, the moisture content of the air-dried bamboo strips in step 1 and the pretreated bamboo strips in step 1 is 10-15%.

[0008] Preferably, the air-drying storage time in step 1 is 30-180 days; and the natural air-drying time in step 3 is 48 hours.

[0009] Preferably, the fixture includes a base plate and two oppositely arranged vertical plates fixed on the base plate, the distance between the two vertical plates is the same as the diameter of the cylindrical mold, a through hole is opened at the top of the vertical plate, a screw is passed through the through hole, and a nut is threaded on the screw.

[0010] Preferably, the minimum curvature of the bamboo compression spring made of bamboo strips with a thickness of 2 mm is 0.05 mm. -1 , maximum 0.1mm -1 The minimum curvature of a bamboo compression spring made of 3mm thick bamboo strips is 0.033mm -1 , the maximum is 0.067mm -1 The minimum curvature of a bamboo compression spring made of 4mm thick bamboo strips is 0.025mm -1 , maximum 0.05mm -1 The minimum curvature of a bamboo compression spring made of 5mm thick bamboo strips is 0.02mm. -1 , maximum 0.04mm -1 .

[0011] Compared with the existing technology, the present invention has the following advantages: the present invention uses sodium hydroxide solution to treat bamboo strips to remove part of the lignin and cellulose, which can increase the softness of the bamboo strips and produce high-curvature bamboo compression springs. Compared with traditional hot bending processing methods, the bamboo compression springs have higher stiffness.

[0012] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the process of manufacturing a high-curvature and high-rigidity bamboo compression spring according to Example 1 of the present invention.

[0014] Figure 2 Schematic diagram of the bamboo compression spring prepared in the present invention.

[0015] Figure 3 Schematic diagram of the structure of the clamp used in the present invention.

[0016] Figure 4 This is a photo of the bamboo compression spring prepared in Example 3 of the present invention.

[0017] Description of reference numerals: 1—base plate; 2—vertical plate; 3—screw; 4—cylindrical mold. DETAILED DESCRIPTION

[0018] Example 1 This embodiment discloses a method for making a high-curvature and high-rigidity bamboo compression spring. Figure 1 As shown, the production method includes: Step 1: Cut the bamboo into strips, and store them for 100 days under natural air drying; the strips have a thickness of 2 mm, a length of 480 mm, and a width of 20 mm; Step 2: Immerse the air-dried bamboo strips in a sodium hydroxide solution at a temperature of 80° C. and a concentration of 8 wt %, keep the solution for 4 hours, then remove the strips, rinse with clean water to remove excess sodium hydroxide solution, and air-dry them at room temperature for 48 hours to obtain pretreated bamboo strips; Step 3: Wrap the pre-treated bamboo strips obtained in step 2 in the spiral groove of the cylindrical mold and fix them with a metal clamp for 24 hours to set the shape. Finally, demould to obtain the bamboo compression spring. Figure 2 shown.

[0019] In this embodiment, the diameter of the cylindrical mold is 40 mm, the width of the rectangular cross-section of the spiral groove is 2 mm, and the length is 20 mm, which is just enough to fit the bamboo strips into the spiral groove.

[0020] In this embodiment, the moisture content of the air-dried bamboo strips in step 1 and the pre-treated bamboo strips in step 1 is 12%.

[0021] Example 2 The method for manufacturing a high-curvature and high-rigidity bamboo compression spring disclosed in this embodiment is the same as the method in Example 1, except that: the length of the bamboo strip in step 1 is 285 mm; and the diameter of the cylindrical mold is 30 mm.

[0022] Example 3 The method for manufacturing a high-curvature and high-rigidity bamboo compression spring disclosed in this embodiment is the same as the method in Example 1, except that: the length of the bamboo strip in step 1 is 320 mm; and the diameter of the cylindrical mold is 20 mm.

[0023] Example 4 The method for making a high-curvature, high-rigidity bamboo compression spring disclosed in this embodiment is the same as that in Example 1, except that: in step 1, the bamboo strip is 950 mm long, 3 mm thick, and 12 mm wide; the diameter of the cylindrical mold is 60 mm; and the width of the rectangular cross-section of the spiral groove is 3 mm. Figure 4 This is a photo of the bamboo compression spring prepared in this example.

[0024] Example 5 The method for manufacturing a high-curvature and high-rigidity bamboo compression spring disclosed in this embodiment is the same as the method in Example 1, except that: the bamboo strip in step 1 is 715 mm in length, 3 mm in thickness, and 12 mm in width; the diameter of the cylindrical mold is 45 mm; and the concentration of the sodium hydroxide solution in step 2 is 14 wt %.

[0025] Example 6 The method for manufacturing a high-curvature and high-rigidity bamboo compression spring disclosed in this embodiment is the same as the method in Example 1, except that: in step 1, the bamboo strip is 480 mm in length, 3 mm in thickness, and 12 mm in width; the diameter of the cylindrical mold is 30 mm, and the width of the rectangular cross-section of the spiral groove is 3 mm; and the concentration of the sodium hydroxide solution in step 2 is 16 wt %.

[0026] Comparative Example 1 A bamboo compression spring with a diameter of 50 mm was produced using the method disclosed in Publication No. CN204327825 U (using heat-softening, bending, and shaping). The bamboo strips used to prepare the bamboo compression spring were 2 mm thick, 480 mm long, and 20 mm wide.

[0027] The bamboo compression spring with a diameter of 50mm manufactured by heating, softening and bending is generally the limit. If the diameter is smaller, such as 40mm, the bamboo fiber will break and spread out and cannot be formed.

[0028] Comparative Example 2 A bamboo compression spring with a diameter of 65 mm was obtained by the method disclosed in publication number CN204327825 U. The bamboo strips used to prepare the bamboo compression spring had a thickness of 3 mm, a length of 620 mm, and a width of 12 mm.

[0029] The stiffness of the bamboo compression springs in Examples 1-6 and Comparative Example 1 was tested to obtain the data in Table 1.

[0030] Table 1 Spring stiffness data of bamboo compression spring The data in Table 1 show that the bamboo strips used in Examples 1 and 2 can be used to produce bamboo compression springs with smaller diameters than those in Comparative Example 1, whereas the method in Comparative Example 1 cannot produce bamboo compression springs with diameters of 40 mm or 30 mm. The 60 mm diameter bamboo compression spring produced in Example 3 exhibits higher stiffness than the 60 mm diameter bamboo compression spring produced in Comparative Example 2. Furthermore, the smaller the diameter of the bamboo compression spring, the higher the stiffness.

[0031] Example 5 This embodiment discloses a method for manufacturing a high-curvature and high-rigidity bamboo compression spring, which comprises: Step 1: Cut the bamboo into strips, air-dry and store them for 180 days; the strips have a thickness of 5 mm, a length of 750 mm and a width of 25 mm; Step 2: Immerse the air-dried bamboo strips in a sodium hydroxide solution with a temperature of 95° C. and a concentration of 18 wt %, keep the solution for 5 hours, then remove the strips, rinse with clean water to remove excess sodium hydroxide solution, and air-dry them at room temperature for 48 hours to obtain pretreated bamboo strips; Step 3: Wrap the pretreated bamboo strips obtained in step 2 in the spiral groove of the cylindrical mold for five turns, and fix them with a metal clamp for 24 hours to set the shape. Finally, demold the bamboo compression spring.

[0032] In this embodiment, the diameter of the cylindrical mold is 40 mm, the width of the rectangular cross section of the spiral groove is 5 mm, and the length is 25 mm, which is just enough to fit the bamboo strips into the spiral groove.

[0033] The curvature of the bamboo compression spring prepared in this embodiment is 0.025 mm -1 , the stiffness is 4.2834N / mm.

[0034] Example 6 This embodiment discloses a method for manufacturing a high-curvature and high-rigidity bamboo compression spring, which comprises: Step 1: Cut the bamboo into strips, and store them in an air-dried state for 30 days; the strips have a thickness of 2 mm, a length of 200 mm, and a width of 15 mm; Step 2: Immerse the air-dried bamboo strips in a sodium hydroxide solution with a temperature of 35° C. and a concentration of 5 wt %, keep the solution for 2 hours, then remove the strips, rinse with clean water to remove excess sodium hydroxide solution, and air-dry them at room temperature for 48 hours to obtain pretreated bamboo strips; Step 3: Wrap the pretreated bamboo strips obtained in step 2 in the spiral groove of the cylindrical mold for three turns, and fix them with a metal clamp for 24 hours to set the shape. Finally, demold the bamboo compression spring.

[0035] In this embodiment, the diameter of the cylindrical mold is 20 mm, the width of the rectangular cross section of the spiral groove is 2 mm, and the length is 15 mm, which is just enough to fit the bamboo strip into the spiral groove.

[0036] The curvature of the bamboo compression spring prepared in this example is 0.05 mm -1 , the stiffness is 3.289N / mm.

[0037] Example 7 This embodiment discloses a method for manufacturing a high-curvature and high-rigidity bamboo compression spring, which comprises: Step 1: Cut the bamboo into bamboo strips with a circular cross section, and store them in an air-dried state for 50 days; the bamboo strips have a diameter of 4 mm and a length of 450 mm; Step 2: Immerse the air-dried bamboo strips in a sodium hydroxide solution with a temperature of 60° C. and a concentration of 10 wt %, keep the solution for 4 hours, then remove the strips, rinse with clean water to remove excess sodium hydroxide solution, and air-dry them at room temperature for 48 hours to obtain pretreated bamboo strips; Step 3: Wrap the pretreated bamboo strips obtained in step 2 in the spiral groove of the cylindrical mold and fix them with a metal clamp for 24 hours to set the shape. Finally, demold the bamboo compression spring.

[0038] In this embodiment, the diameter of the cylindrical mold is 25 mm, the width of the rectangular cross section of the spiral groove is 2 mm, and the length is 15 mm, which is just enough to fit the bamboo strip into the spiral groove.

[0039] The curvature of the bamboo compression spring prepared in this example is 0.04 mm -1 , the stiffness is 0.655N / mm (number of turns n=5).

[0040] In this embodiment, the diameter of the bamboo strips can also be 3mm or 5mm, and the length can also be 150mm, 250mm, 350mm, 550mm, 650mm, or 750mm, which can be selected according to the application requirements of the prepared bamboo compression spring.

[0041] like Figure 3 As shown, the metal clamp in the embodiment includes a base plate 1 and two oppositely arranged vertical plates 2 fixed on the base plate 1. The distance between the two vertical plates 2 is the same as the diameter of the cylindrical mold 4. A through hole is opened at the top of the vertical plate 2, and a screw 3 is passed through the through hole. A nut is threaded on the screw 3.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for manufacturing a high-curvature and high-rigidity bamboo compression spring, characterized in that: The preparation method comprises: Step 1: Cut the bamboo into strips and air-dry them for storage; Step 2: immersing the air-dried bamboo strips in step 1 in a sodium hydroxide solution for alkaline pretreatment, rinsing with clean water to remove excess sodium hydroxide solution after the alkaline pretreatment, and finally air-drying naturally at room temperature to obtain pretreated bamboo strips; Step 3: Wrap the pre-treated bamboo strips obtained in step 2 in the spiral groove of the cylindrical mold and fix it with a clamp to shape it. Finally, demould to obtain a bamboo compression spring with a curvature of 0.02-0.1mm. -1 , stiffness is 0.3-6.5N / mm.

2. The method for manufacturing a high-curvature and high-rigidity bamboo compression spring according to claim 1, characterized in that: The bamboo strips are rectangular or circular in cross section. The bamboo strips with rectangular cross section have a thickness of 2-5 mm, a length of 200-950 mm, and a width of 10-25 mm. The bamboo strips with circular cross section have a diameter of 3-5 mm and a length of 150-750 mm.

3. The method for manufacturing a high-curvature and high-rigidity bamboo compression spring according to claim 1, characterized in that: The temperature of the sodium hydroxide solution in step 2 is 35° C.-95° C., and the concentration is 5-18 wt %.

4. The method for manufacturing a high-curvature and high-rigidity bamboo compression spring according to claim 1, characterized in that: The time of alkali pretreatment in step 2 is 2-5 hours.

5. The method for manufacturing a high-curvature and high-rigidity bamboo compression spring according to claim 1, characterized in that: The moisture content of the air-dried bamboo strips in step 1 and the pre-treated bamboo strips in step 1 is 10-15%.

6. The method for manufacturing a high-curvature and high-rigidity bamboo compression spring according to claim 1, characterized in that: The air-drying storage time in step 1 is 30-180 days; the natural air-drying time in step 3 is 48 hours.

7. The method for manufacturing a high-curvature and high-rigidity bamboo compression spring according to claim 1, characterized in that: The fixture includes a base plate and two oppositely arranged vertical plates fixed on the base plate. The distance between the two vertical plates is the same as the diameter of the cylindrical mold. A through hole is opened at the top of the vertical plate, a screw is passed through the through hole, and a nut is threaded on the screw.

8. The method for manufacturing a high-curvature and high-rigidity bamboo compression spring according to claim 2, characterized in that: The minimum curvature of a bamboo compression spring made of 2mm thick bamboo strips is 0.05mm -1 , maximum 0.1mm -1 The minimum curvature of a bamboo compression spring made of 3mm thick bamboo strips is 0.033mm -1 , the maximum is 0.067mm -1 The minimum curvature of a bamboo compression spring made of 4mm thick bamboo strips is 0.025mm -1 , maximum 0.05mm -1 The minimum curvature of a bamboo compression spring made of 5mm thick bamboo strips is 0.02mm. -1 , maximum 0.04mm -1 .

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