A method and device for reinforcing carbon fiber multifilament spline

Abstract

The present invention relates to a carbon fiber multifilament spline reinforcement method and device, which solves the technical problems of unsatisfactory reinforcement effect and inaccurate test results of existing carbon fiber multifilaments, and is provided with an upper pressing plate, a lower pressing plate, a transmission pressurizing device, a transmission device, a thermal insulation layer and a control system, wherein the upper pressing plate, the lower pressing plate, the transmission pressurizing device and the transmission device are arranged in the thermal insulation layer, and the control system is connected to a computer. The present invention also provides a carbon fiber multifilament spline reinforcement method. The present invention can be used in the field of carbon fiber multifilament spline preparation.

Description

Technical Field

[0001] The present invention relates to a carbon fiber detection device, in particular to a carbon fiber multifilament spline reinforcement method and device. Background Art

[0002] Carbon fiber refers to a new type of high-strength, high-modulus fiber material with a carbon content of more than 90%. It has a series of excellent properties such as high temperature resistance, friction resistance, electrical conductivity, thermal conductivity, and corrosion resistance. Therefore, it is widely used in aerospace, sports and leisure, lightweight automobiles, wind turbine blades and other fields.

[0003] With the breakthrough of domestic carbon fiber technology, various types of carbon fiber have achieved stable localization, and the characterization of carbon fiber performance indicators is particularly important. Among them, the mechanical properties of carbon fiber multifilament is an important indicator of carbon fiber, and the test is carried out according to the "Test Method for Tensile Properties of Carbon Fiber Multifilament" GB / T3362-2017. The standard stipulates the width, material and thickness of the reinforcement sheet, but does not clarify the specific reinforcement operation.

[0004] At present, there are two reinforcement technologies: manual reinforcement and resin dipping and curing. Both technologies have shortcomings, which affect the quality of carbon fiber multifilament reinforcement, and the efficiency cannot be guaranteed, so that the mechanical properties test is affected and even the test results are inaccurate.

[0005] At present, the reinforcement of carbon fiber multifilament strips in China is mainly done manually. The two ends of the cured strips are reinforced on kraft paper with resin glue, covered with a pressing plate or other heavy objects, and then placed in an oven for heating and curing.

[0006] However, this method has the following main problems: 1. It is difficult to ensure the consistency of the specimen gauge length between the reinforcing sheets, which increases the test error; 2. The alignment between the reinforcing sheets and the fibers is prone to failure, affecting the test results; 3. The amount of glue cannot be controlled by manual operation, resulting in glue on connected boards, glue at the roots, and debonding; 4. Manual gluing is inefficient and affects personal and environmental hygiene; 5. The use of an oven poses a safety hazard of burns.

[0007] A Chinese invention patent application with publication number CN111337333A discloses an apparatus and method for preparing carbon fiber multifilament tensile test specimens, which are used to press a reinforcing sheet onto a carbon fiber multifilament wound on a sample preparation frame, wherein the sample preparation frame is surrounded by a cylindrical frame, and includes: a first clamping plate, a second clamping plate covering the first clamping plate, and a locking structure for fixing the first clamping plate to the second clamping plate; a limiting groove is provided on the first clamping plate and / or the second clamping plate, and the limiting groove can respectively accommodate the symmetrical two side frames of the sample preparation frame to achieve relative fixation between the first clamping plate and / or the second clamping plate and the sample preparation frame, and the first clamping plate and the second clamping plate also have a pressing surface for pressing the reinforcing sheet onto the carbon fiber multifilament.

[0008] However, this method has the following main problems:

[0009] 1. After the tow is dipped in glue, it needs to be dried at room temperature to ensure that the solvent evaporates. However, the drying time varies depending on the size of the tow. Therefore, this technology cannot take into account the curing timeliness of the reinforcement, affecting the reinforcement quality;

[0010] 2. After the tow is impregnated with glue and solidified, the tow is in a wet state. This technology can easily cause the fibers at the reinforcement end to be dispersed and flattened after reinforcement, affecting the test results;

[0011] 3. The applied pressure cannot be controlled to a certain extent, so the strengthening effect cannot be guaranteed;

[0012] 4. There are no measures to control the amount of resin glue, and the reinforcement quality cannot be ensured.

[0013] The Chinese invention patent application with publication number CN108303296A discloses a sample preparation method for tensile testing of high-model carbon fiber multifilaments, but the patent does not specify the strengthening operation technology. Summary of the invention

[0014] The present invention aims to solve the technical problems of unsatisfactory reinforcement effect and inaccurate test results of existing carbon fiber multifilament strips, and provides a method and device for reinforcing carbon fiber multifilament strips with better reinforcement effect and accurate test results.

[0015] To this end, the present invention provides a carbon fiber multifilament spline reinforcement device, which is provided with an upper pressing plate, a lower pressing plate, a transmission pressurizing device, a transmission device, a thermal insulation layer and a control system. The upper pressing plate, the lower pressing plate, the transmission pressurizing device and the transmission device are arranged in the thermal insulation layer, and the control system is connected to a computer; the transmission pressurizing device is used to drive the upper pressing plate to move up and down and can apply a set pressure; the transmission device is used to drive the lower pressing plate to move forward and backward; the thermal insulation layer plays a role in protecting the temperature uniformity of the temperature field without heat loss; the control system can control temperature, pressure, time and displacement. The upper pressing plate is used for heating, pressurizing, and moving up and down; the lower pressing plate is used for heating, placing splines, and moving forward and backward.

[0016] Preferably, the upper pressing plate and the lower pressing plate are provided with control sensors, and the control sensors are used to sense and control temperature, pressure and displacement.

[0017] The present invention also provides a carbon fiber multifilament spline reinforcement method, which comprises the following steps:

[0018] (1) Through the control system, the lower pressure plate of the reinforcement device is ejected to serve as a reinforcement working platform; (2) Kraft paper is placed on the left and right sides of the lower pressure plate, with the width equal to that of the lower pressure plate and the edges flush with the lower pressure plate; (3) The multifilament spline to be reinforced is placed on the dotted line of the kraft paper; (4) Reinforcement resin is taken with a syringe, and the multifilament spline on the kraft paper is vertically injected from the top to the edge of the kraft paper; (5) A layer of kraft paper is covered on each side of the lower pressure plate, aligned with the edge of the bottom kraft paper; (6) Through the control system, the lower pressure plate is rebounded to its original position; (7) Through the control system, the upper pressure plate is moved down to contact the upper kraft paper; (8) After curing, the temperature is lowered and taken out for testing.

[0019] Preferably, in step (4), 0.5 to 2.0 g of resin is uniformly injected starting from a position 5 mm away from the edge of the kraft paper.

[0020] Preferably, in step (8), the parameters of the strengthening device are: temperature 80-105°C, heating rate 40-80°C / min, pressure 5-10 kN, time 30-90 min;

[0021] The present invention has the following beneficial effects:

[0022] 1. Realize automatic control in a closed environment, ensuring controllable temperature, pressure and time;

[0023] 2. Improve the alignment of reinforced kraft paper to avoid tilting or misalignment;

[0024] 3. The multifilament spline is accurately positioned, which improves the quality of strengthening operation;

[0025] 4. According to the results of resin thermal analysis, the setting of curing curve is optimized, thereby improving the curing quality and efficiency of multifilament reinforcement;

[0026] 5. The operation is more convenient, the detection efficiency is improved, and the personnel cost is reduced;

[0027] 6. Avoid the possibility of misalignment of reinforcing paper due to operational errors when transferring the reinforcing plate;

[0028] 7. Avoid board falling off and board connection caused by uncontrollable pressure;

[0029] 8. The operating environment is optimized to avoid the difficult-to-clean phenomenon caused by dripping when manually applying resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the present invention;

[0031] Figure 2 To strengthen the design drawings with kraft paper.

[0032] In the figure, 1. upper pressure plate; 2. lower pressure plate; 3. transmission pressure device; 4. transmission device; 5. insulation layer; 6. control system. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with embodiments.

[0034] like Figure 1 As shown, the present invention provides a carbon fiber multifilament spline reinforcement device, which is provided with an upper pressing plate 1, a lower pressing plate 2, a transmission pressurizing device 3, a transmission device 4, a thermal insulation layer 5 and a control system 6. The upper pressing plate 1, the lower pressing plate 2, the transmission pressurizing device 3 and the transmission device 4 are arranged in the thermal insulation layer 5, and the control system 6 is connected to a computer; the transmission pressurizing device 3 is used to drive the upper pressing plate 1 to move up and down and pressurize; the thermal insulation layer 5 plays a role in protecting the temperature uniformity of the temperature field without heat loss; the control system 6 can control temperature, pressure, time and displacement. The upper pressing plate 1 is used for heating, pressurizing, and moving up and down. The lower pressing plate 2 is used for heating, placing splines, and moving back and forth. The upper and lower pressing plates are provided with temperature, pressure, and displacement control sensors.

[0035] Example 1

[0036] Take 12k carbon fiber spline as an example:

[0037] 1. The width of the reinforcement sheet (i.e. the distance between the dotted lines) is set to 15mm kraft paper;

[0038] 2. Through the control system, the lower pressure plate of the reinforcement device is ejected to serve as a reinforced working platform;

[0039] 3. Place kraft paper on the left and right sides of the lower pressing plate, with the width equal to the lower pressing plate and the edges flush with the lower pressing plate;

[0040] 4. Place the multifilament spline to be strengthened on the dotted line of the kraft paper;

[0041] 5. Use a syringe to take the reinforcing resin, and evenly inject 1.0g of resin from the multifilament strip on the kraft paper vertically from the top, about 5mm away from the edge of the kraft paper;

[0042] 6. Cover the left and right sides of the lower pressing plate with a layer of kraft paper, aligning with the edge of the bottom kraft paper;

[0043] 7. Through the control system, the lower pressure plate is rebounded to its original position;

[0044] 8. Through the control system, the upper pressing plate is moved down to contact the upper kraft paper;

[0045] 9. Set the parameters of the strengthening device: temperature 85°C, heating rate 50°C / min, pressure 8kN, time 45min;

[0046] 10. After curing, cool down and take out for testing.

[0047] In this embodiment, the entire sample preparation process requires one operator, takes one hour, and the sample qualification rate is 90%.

[0048] Comparative Example 1

[0049] Take 12k carbon fiber spline as an example:

[0050] 1. Place the prepared kraft paper on the reinforcing plate, ensuring a good spacing between the left and right sides;

[0051] 2. Apply resin glue to the kraft paper on the left and right sides;

[0052] 3. Place the strip perpendicular to the kraft paper and on the location coated with resin glue;

[0053] 4. Cover the strip with a layer of kraft paper;

[0054] 5. After strengthening, cover it with a pressure plate or other heavy objects;

[0055] 6. Place in an oven at (85±1)℃ and heat to cure for 1h;

[0056] 7. After curing, cool down and take out for testing.

[0057] The entire sample preparation process requires one operator, takes 1.5 hours, and the sample qualification rate is 100%.

[0058] By comparing Comparative Example 1 with Example 1, it can be seen that for the same carbon fiber spline, the time taken by Comparative Example 1 is 1.5 times that of Example 1, and the qualified rate of the spline is increased by 10%. It can be seen that the method for preparing the spline in Example 1 is faster and has a higher qualified rate.

[0059] Embodiment 2:

[0060] Take 48k carbon fiber spline as an example:

[0061] 1. The width of the reinforcement sheet (i.e. the distance between the dotted lines) is set to 20mm kraft paper;

[0062] 2. Through the control system, the lower pressure plate of the reinforcement device is ejected to serve as a reinforced working platform;

[0063] 3. Place kraft paper on the left and right sides of the lower pressing plate, with the width equal to the lower pressing plate and the edges flush with the lower pressing plate;

[0064] 4. Place the multifilament spline to be strengthened on the dotted line of the kraft paper;

[0065] 5. Use a syringe to take the reinforcing resin, and evenly inject 1.6g of resin from the multifilament strip on the kraft paper vertically from the top, about 5mm away from the edge of the kraft paper;

[0066] 6. Cover the left and right sides of the lower pressing plate with a layer of kraft paper, aligning with the edge of the bottom kraft paper;

[0067] 7. In the control system of the strengthening device, operate to make the lower pressure plate rebound to its original position;

[0068] 8. Operate the control system to move the upper pressing plate downward until it contacts the upper kraft paper;

[0069] 9. Set the parameters of the strengthening device: temperature 100℃, heating rate 70℃ / min, pressure 10kN, time 60min;

[0070] 10. After curing, cool down and take out for testing.

[0071] In this embodiment, the entire sample preparation process requires one operator, takes 1.25 hours, and the sample qualification rate is 80%.

[0072] Comparative Example 2

[0073] Take 48k carbon fiber spline as an example:

[0074] 1. Place the prepared kraft paper on the reinforcing plate, ensuring a good spacing between the left and right sides;

[0075] 2. Apply resin glue to the kraft paper on the left and right sides;

[0076] 3. Place the strip perpendicular to the kraft paper and on the location coated with resin glue;

[0077] 4. Cover the strip with a layer of kraft paper;

[0078] 5. After strengthening, cover it with a pressure plate or other heavy objects;

[0079] 6. Place in a (100±1)℃ oven for heating and curing for 1.5h;

[0080] 7. After curing, cool down and take out for testing.

[0081] The entire sample preparation process requires one operator, takes two hours, and the sample qualification rate is 100%.

[0082] By comparing Comparative Example 2 with Example 2, it can be seen that for the same carbon fiber spline, the time taken by Comparative Example 2 is 1.6 times that of Example 2, and the qualified rate of the spline is increased by 15%. It can be seen that the method for preparing the spline in Example 2 is faster and has a higher qualified rate.

[0083] However, what is described above is only a specific embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the scope of protection of the present invention should still fall within the scope covered by the claims of the present invention.

Claims

1. A method for reinforcing a carbon fiber multifilament spline, characterized in that: It uses a carbon fiber multifilament spline reinforcement device, which is provided with an upper pressing plate, a lower pressing plate, a transmission pressurizing device, a transmission device, a thermal insulation layer and a control system. The upper pressing plate, the lower pressing plate, the transmission pressurizing device and the transmission device are arranged in the thermal insulation layer, and the control system is connected to a computer; the transmission pressurizing device is used to drive the upper pressing plate to move up and down and can apply a set pressure; the transmission device is used to drive the lower pressing plate to move forward and backward; the thermal insulation layer protects the temperature uniformity of the temperature field without heat loss; the control system can control temperature, pressure, time and displacement; the upper pressing plate is used for heating, pressurizing and moving up and down; the lower pressing plate is used for heating, placing splines and moving forward and backward; the upper pressing plate and the lower pressing plate are provided with control sensors, and the control sensors are used to sense and control temperature, pressure and displacement; The method comprises the following steps: (1) Through the control system, the lower pressure plate of the reinforcement device is ejected to serve as a reinforced working platform; (2) Place kraft paper on the left and right sides of the lower pressing plate, with the width equal to the lower pressing plate and the edges flush with the lower pressing plate; (3) Place the multifilament spline to be strengthened on the dotted line of the kraft paper; (4) Use a syringe to take the reinforcing resin, and inject the resin at the edge of the kraft paper from the top of the multifilament strip vertically on the kraft paper; (5) Cover the left and right sides of the lower pressing plate with a layer of kraft paper, aligning with the edge of the bottom kraft paper; (6) The lower pressure plate is rebounded to its original position through the control system; (7) through the control system, the upper pressing plate is moved down to contact the upper kraft paper; (8) After curing, cool down and take out for testing.

2. The carbon fiber multifilament spline reinforcement method according to claim 1, characterized in that: In the step (4), 0.5 to 2.0 g of resin is uniformly injected starting from a position 5 mm away from the edge of the kraft paper.

3. The carbon fiber multifilament spline reinforcement method according to claim 1, characterized in that: In the step (8), the parameters of the strengthening device are: temperature 80-105°C, heating rate 40-80°C / min, pressure 5-10 kN, and time 30-90 min.

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