Industrial preparation device and method for chopped recycled carbon fiber

Abstract

An industrialized production apparatus and method for chopped regenerated carbon fibers. The apparatus comprises a sequentially arranged sizing system, a sizing system, a sizing control system, a pre-drying system, a chopping system, and a secondary drying system. The present invention not only enables orderly and uniform sizing of the regenerated carbon fibers and standard modular continuous chopping, but also ensures good particle size and uniform bulk density during post-processing, facilitating continuous feeding and precise metering. Furthermore, at processing temperatures, the regenerated chopped carbon fibers exhibit good fiber opening, resin dispersibility, and high-temperature stability of the composite interface.

Description

Technical Field

[0001] The invention relates to regenerated carbon fibers, and in particular to an industrial preparation device and method for chopped regenerated carbon fibers. Technical Background

[0002] The focus of domestic and international attention on the recycling technology of recycled carbon fiber is still on the efficient recycling technology of carbon fiber after the end of the life of carbon fiber composite materials, and the comparative study of economic and environmental performance. In view of the characteristics of recycled carbon fiber and the subsequent application equipment and technology, there have been reports abroad on the research of recycling carbon fiber to prepare new high-performance blended yarn for lightweight structures; Jack Howarth of Sheffield University in the United Kingdom and Joseph Heil of North Carolina State University in the United States reported on the use of recycled carbon fiber to make electromagnetic shielding materials, but there are very few reports on specific recycling technology and equipment information and patents.

[0003] The most relevant patent for domestic recycled carbon fiber pre-treatment, such as sizing, chopped granulation, drying, and metering equipment and technology, is CN 110042663 A, a method for manufacturing carbon fiber bundles. The key features of its rights involve the types of sizing agent raw materials for unsized carbon fibers, and the compounding and sizing technical parameters, which are different from those of the present invention.

[0004] The sizing agent thermoplastic polymer materials involved in the present invention include but are not limited to hydrophilic polyurethane and polyamide, all of which are commercially available thermoplastic PI\PA\PU and PSF powders, which are ground, grafted chemically and gas-phase synthesized water-based graphene, homemade thermosetting epoxy resin physically blended and modified, and emulsified at high speed (7000-5000rpm); the concentration is 5.5% to 6.5%, and the sizing rate is 3.0% to 5.0%; the pre-drying temperature after sizing is 85±10°C in the operating temperature zone; the drying time is 45±15min; and the vacuum is 30±15Kpa; from the sizing effect, the present invention not only enables the regenerated carbon fiber to be orderly and uniformly sizing and standard modular continuous chopped, but also enables the chopped regenerated carbon fiber to have good granularity and uniform bulk density during the post-processing process, and is easy to achieve continuous feeding and precise metering, and at the processing temperature, the regenerated chopped carbon fiber also has good fiber opening, resin dispersibility, and high-temperature stability of the composite interface. Summary of the Invention

[0005] Aiming at the problems that it is difficult to make the regenerated carbon fibers sizing in an orderly and uniform manner, it is difficult to achieve standardized continuous chopping of the sized regenerated carbon fibers, it is difficult for the chopped regenerated carbon fibers to have a regular particle morphology, the sizing rates of the particles vary greatly, the bulk density of the particles is low, and it is difficult to achieve continuous feeding and precise metering in the existing industrial preparation of chopped regenerated carbon fibers, the present invention provides an industrial preparation device and a preparation method for chopped regenerated carbon fibers. The present invention not only enables the regenerated carbon fibers to be sizing in an orderly and uniform manner and continuously chopped in a standard modular manner, but also the chopped regenerated carbon fibers have good particle properties and uniform bulk density during post-processing, making it easy to achieve continuous feeding and precise metering. Moreover, at the processing temperature, the regenerated chopped carbon fibers also have good fiber opening properties, resin dispersibility, and high-temperature stability of the composite interface.

[0006] The technical solutions of the present invention are as follows:

[0007] An industrialized preparation device for chopped recycled carbon fiber is characterized in that the device consists of a slurry supply system, a sizing system, a slurry control system, a pre-drying system, a chopped carbon fiber system and a secondary drying system arranged in sequence:

[0008] The slurry supply system consists of an agitator, a slurry supply tank, and a slurry supply pump. The agitator is a metal blade type, controlled by a frequency converter. The slurry supply pump is a carbon fiber reinforced PPS pneumatic pump, located on the ground in the middle between the slurry supply tank and the slurry supply tank, and is fixed to the ground with metal bolts. The bottom of the slurry supply tank has a discharge pipe valve and a sewage valve connected to the left pipe opening of the slurry supply pump. The right side of the slurry supply pump inlet is connected to the discharge valve at the bottom of the slurry supply tank and the slurry control tank. The left valve of the slurry supply pump outlet is connected to the return pipe opening at the top of the slurry supply tank, and the right valve is connected to the inlet of the sizing agent distribution pipe upright on the left side of the slurry supply tank.

[0009] The sizing system consists of a first constant volume grid assembly, a sizing tank, a sizing agent, regenerated carbon fiber and a sizing agent distribution pipe: wherein, the first constant volume grid assembly is composed of N pairs of concave column grids and convex column grids with concave columns and convex columns fitted in reverse; the regenerated carbon fiber is quantitatively and orderly confined in the first constant volume grid assembly; the first constant volume grid assembly is horizontally immersed and placed on the bottom of the sizing tank by its own weight; the sizing agent distribution pipe is located between the left side of the constant volume grid assembly and the left inner wall of the sizing tank, and is fixed in a vertical manner in the clamp at the right end of the two brackets welded up and down on the left inner wall of the sizing tank; the sizing agent distribution pipe is evenly distributed with a row of unidirectional nozzles along the axial direction, and the nozzles are perpendicular to the left inner wall of the sizing tank; a discharge pipe mouth is provided on the right side of the bottom of the sizing tank, and the discharge pipe mouth is connected to the right pipe mouth of the slurry supply pump through a valve and a pipeline with a metal pipe flange.

[0010] The grouting control system consists of a type clamping steel shaft, a grouting plate, a second constant volume grid assembly, a grouting back plate, a grouting control bracket and a grouting control tray: wherein the type clamping steel shaft consists of an upper clamping shaft and two lower supporting shafts, the left and right ends of the upper clamping shaft are respectively fixed with bolts to the middle of the left and right sides of the top beam from the outside to the inside of the grouting control bracket, and the left and right ends of the two lower supporting shafts are respectively fixed with bolts to the left and right bottom beams of the grouting control bracket from the outside to the inside; the grouting plate is made of lightweight alloy steel, and its plate size is the same as the end face size and shape of the constant volume grid, and its grouting power is driven by compressed air, and the compressed air high-pressure hose is respectively connected to the sealing short section in the middle and upper part of the grouting plate and the sealing short section at the bottom part with metal quick connectors; the upper, middle and lower parts of the right side of the grouting back plate are respectively welded to the middle of the upper, middle and lower beams on the right side of the grouting control bracket. The slurry pressing plate moves from left to right under the drive of compressed air, squeezing the sized regenerated carbon fibers in the second constant volume grid assembly; the extruded sizing agent falls into the slurry control tray at the bottom of the slurry control bracket, and the bottom pipe of the slurry control tray is connected to the pipe flange of the slurry supply pump.

[0011] The pre-drying system consists of a vacuum negative pressure oven, a first constant volume grid assembly and slurry pressed carbon fibers, wherein: the gas and moisture exhausted from the vacuum oven are led to the outside through an exhaust pipe and discharged at high altitude; the four movable pulleys of the vacuum negative pressure oven are all equipped with a brush device.

[0012] The chopped carbon fiber system consists of a cutter, a chopped carbon fiber collection bucket, a PC dust cover, and pre-dried recycled carbon fiber. The dust generated during the chopped carbon fiber chopped carbon fiber is transported to the dust collection system through the suction pipe on the top of the PC dust cover.

[0013] The secondary drying system consists of a hot air dryer and chopped recycled carbon fibers. The water vapor generated during the secondary drying process is discharged outdoors through an exhaust pipe at the top of the hot air dryer. The four movable pulleys of the hot air dryer are all equipped with brushes.

[0014] The exhaust (steam) and dust exhaust pipes of the pre-baking system, short-cut system and secondary baking system adopt carbon fiber reinforced plastic hoses with carbon fiber reinforced plastic flanges, and the connection method is carbon fiber reinforced plastic bolts and nuts and carbon fiber reinforced thermoplastic elastomer sealing gaskets.

[0015] The method for preparing regenerated carbon fibers using the industrialized preparation device for chopped regenerated carbon fibers comprises the following steps:

[0016] 1) The sizing agent is in place: close the bottom valve of the slurry supply tank and the valve on the right side of the slurry supply pump, start the slurry supply pump to pump the slurry into the slurry supply tank through the slurry supply tank drain valve for storage. When the sizing agent level pumped into the slurry supply tank reaches 80%, close the drain valve, establish the slurry supply tank self-circulation, turn on the agitator, and adjust the opening by 50% by frequency conversion to keep the sizing agent components uniform.

[0017] 2) Assembly and installation of regenerated carbon fiber: A first constant volume grid assembly is formed by N pairs of concave column nets containing a certain amount of regenerated carbon fiber to be sized) and convex column nets with corresponding concave columns and convex columns, and the concave column nets are horizontally flipped 180 degrees along the AB axis and then fitted together. The first constant volume grid assembly is moved into the sizing tank, and the bottoms of the two touch but are not fixed, where N is 4 to 10.

[0018] 3) Sizing the recycled carbon fiber batches of the first constant volume grid assembly: The sizing agent in the sizing tank is passed through the sizing pump and the sizing agent distribution pipe in the same direction nozzle, perpendicular to the left inner wall of the sizing tank, and then collides. After turbulent mixing, it is transformed into laminar flow by reverse force and enters the first constant volume grid assembly horizontally to infiltrate the recycled carbon fiber. When the liquid level of the sizing tank reaches 80%, the sizing agent self-circulation of the sizing tank is established. The sizing tank is immersed for 60±15 seconds. The first constant volume grid assembly after impregnation is removed and the next batch of unsized recycled carbon fibers of the first constant volume grid assembly is sized according to the above operation.

[0019] 4) Slurry control of recycled carbon fiber: Take out the first constant volume grid assembly from the sizing tank and place it horizontally on the type clamping steel shaft of the slurry control system. Rotate each concave column grid horizontally by 180 degrees and reassemble it into the second constant volume grid assembly. Start from the right side of the grouting backboard, turn the grouting plate in turn, with the two fixed ports facing downwards, and align and erect it on the type clamping steel shaft to the right side close to the grouting backboard. Gradually open and increase the compressed air, and control the pressure at 0.20-0.6Mpa. Driven by compressed air, the slurry plate moves to the right to squeeze the sized recycled carbon fiber in the second constant volume grid assembly. The squeezing time is 80-120 seconds. The extruded sizing agent falls into the slurry control tray under the bottom of the slurry control bracket. Open the valve of the slurry control tray and pump the sizing agent into the slurry tank through the slurry supply pump. Stop the compressed air, take out the second constant volume grid assembly unit that has completed the slurry control in turn and transfer it to the recycled carbon fiber pre-baking process. After pre-baking, follow the above operation to enter the first constant volume grid assembly for slurry control after the next batch of sizing.

[0020] 5) Pre-drying the regenerated carbon fiber: Restore the second constant volume grid assembly to the first constant volume grid assembly. Pre-drying process: operating temperature range 85±10°C; drying time 45±15 minutes; vacuum 30±15KPa.

[0021] 6) Chopping of regenerated carbon fiber: Start the cutting machine, take out the pre-baked regenerated carbon fiber, and place it in the feed port of the cutting machine in sequence for chopping. The chopped regenerated carbon fiber falls into the chopped material receiving barrel through the guide chute. Chopped process: cutting frequency 120±60 times / min, cutting length: 3-12MM;

[0022] 7) Secondary drying of chopped recycled carbon fiber: The chopped material collection barrel filled with recycled carbon fiber is sent to the second drying oven for secondary drying. The secondary drying process varies according to the brand of sizing agent: for PI sizing agent: drying at 160-180℃ for 60-80min, drying at 230-240℃ for 20-30min; for high-temperature PA, PU and polyphenolic sizing agents: drying at 160-180℃ for 60-80min; for ordinary PP, PU, ​​PA or conventional thermosetting sizing agents, drying at 100-120℃ for 100-120min.

[0023] 8) When the liquid level in the slurry supply tank is lower than 20%, return to step 1), pump in the prepared sizing agent until the liquid level in the slurry supply tank reaches 80%, and continue subsequent production operations until the production task is completed.

[0024] 9) Equipment cleaning: After completing the production task, all the slurry in the sizing system and the slurry control system will be pumped back into the slurry supply tank; stop the slurry supply pump and the agitator, connect the sewage outlet to a temporary plastic hose, and let the slurry in the slurry supply tank flow into the raw material barrel by gravity pressure difference for storage and reuse next time. Put the used concave column net and convex column net into the slurry tank of the sizing system and fill it with water to 90%. Start the slurry supply pump to establish the slurry system self-circulation, and clean the concave column net, convex column net and the slurry tank; rinse the grouting back plate, grouting plate, type clamping steel shaft and slurry control tray of the slurry control system ③ with a small amount of water; after completing the cleaning of the slurry control system, all the cleaning water is pumped into the slurry supply tank to establish the slurry supply tank self-circulation cleaning; after completing the cleaning of the slurry supply system, discharge the cleaning wastewater through a plastic hose or barrel to the sewage treatment tank for treatment.

[0025] The main advantages of the present invention are: orderly and uniform sizing of recycled carbon fibers; standardized continuous chopping of sized recycled carbon fibers; the chopped recycled carbon fibers have regular particle morphology, and the particle packing density meets the conditions for precise metering and continuous feeding, thus opening up a channel for the application of recycled carbon fibers in the CFRTP field. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a diagram of the industrial preparation device for chopped recycled carbon fiber of the present invention

[0027] Figure 2 This is a process flow chart of sizing and sizing of chopped regenerated carbon fiber of the present invention

[0028] Figure 3 This is a schematic diagram of the combined structure of the first constant volume grid combination (7)

[0029] Figure 4 Schematic diagram of the first constant volume grid changing to the second constant volume grid and its fixed position

[0030] Figure 5 The process flow chart of recycled carbon fiber slurry control

[0031] Figure 6 This is the second constant volume grid combination transformation and slurry control principle diagram DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments and drawings to clearly and completely describe the technical solutions and methods of use of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all belong to the scope of protection of the present invention.

[0033] Please refer to Figure 1 , Figure 1 2. It is a diagram of an industrialized preparation device for chopped regenerated carbon fibers of the present invention. As can be seen from the figure, the industrialized preparation device for chopped regenerated carbon fibers of the present invention is composed of a slurry supply system ①, a sizing system ②, a slurry control system ③, a pre-drying system ④, a chopped system ⑤, and a secondary drying system ⑥, which are arranged in sequence;

[0034] The slurry supply system ① is composed of an agitator 1, a slurry supply tank 2 and a slurry supply pump 3: the stirring blade of the agitator 1 is located in the middle and lower part of the slurry supply tank 2, and is a metal blade type, which is controlled by a frequency converter; the slurry supply pump 3 is a carbon fiber reinforced PPS pneumatic pump, which is located on the ground in the middle between the slurry supply tank 2 and the slurry supply tank 4, and is fixed to the ground with metal bolts. The bottom of the slurry supply tank 2 is composed of a first valve 5 and a second valve 5.1 having a discharge pipe. The second valve 5.1 is connected to the second pneumatic pump valve 3.4 on the left side of the inlet of the slurry supply pump 3. The right side of the inlet of the slurry supply pump is connected to the first pneumatic pump valve 3.3 at the bottom of the slurry supply tank and the control tank, and the valve 12 is connected to the third valve 13.1 on the left side of the outlet; the fourth valve 3.1 on the left side of the outlet of the slurry supply pump 3 is connected to the reflux pipe at the top of the slurry supply tank 2, and the fifth valve 3.2 is connected to the inlet of the sizing agent distribution pipe 10 erected on the left side of the slurry supply tank 4.

[0035] The sizing system ② is composed of a first constant volume grid assembly 7, a sizing tank 4, a sizing agent 8, a regenerated carbon fiber 9 and a sizing agent distribution pipe 10: wherein the first constant volume grid assembly 7 is composed of N pairs of concave column nets 7.4, convex column nets 7.2, and concave columns 7.3 and convex columns 7.1 in reverse order, wherein N is 4 to 10; the regenerated carbon fiber 9 is quantitatively and orderly confined in the first constant volume grid assembly 7; the first constant volume grid assembly 7 is horizontally immersed and placed at the bottom of the sizing tank 4 by its own weight; the sizing agent distribution pipe 10 ... The agent distribution pipe 10 is located between the left side of the constant volume grid assembly 7 and the left inner wall of the sizing tank 4, and is fixed in a vertical manner in the clamp at the right end of the two brackets welded upper and lower on the left inner wall of the sizing tank 4; the sizing agent distribution pipe 10 is evenly distributed with a row of unidirectional nozzles 11 along the axial direction, and the nozzles 11 are perpendicular to the left inner wall of the sizing tank 4; the sizing tank 4 has a discharge pipe opening on the right side of the bottom, and the discharge pipe opening is connected to the right pipe opening of the slurry supply pump 3 through a valve 12 and a pipeline with a metal pipe flange.

[0036] The grouting control system ③ is composed of a type clamping steel shaft 14, a grouting plate 16, a second constant volume grid assembly 18, a grouting back plate 19, a grouting support 20 and a grouting tray 13: wherein the type clamping steel shaft 14 is composed of an upper clamping shaft and two lower supporting shafts, the left and right ends of the upper clamping shaft are respectively fixed by bolts to the middle of the left and right sides of the top beam from the outside to the inside of the grouting support 20, and the left and right ends of the two lower supporting shafts are respectively fixed by bolts to the left and right bottom beams from the outside to the inside of the lower part of the grouting support 20; the grouting plate 16 is made of light alloy steel, and its plate size is the same as the end face size and shape of the constant volume grid. Its grouting power is driven by compressed air, and the compressed air high-pressure hose is respectively connected to the compressed air 17 in the middle and upper part of the grouting plate and the sealing short section 15 at the lower part with a metal quick connector; the right side, middle and lower parts of the grouting back plate 19 are respectively welded to the middle of the upper, middle and lower beams on the right side of the grouting support 20. Driven by compressed air, the slurry pressing plate 16 moves from left to right, squeezing the sized regenerated carbon fibers in the second constant volume grid assembly 18; the extruded sizing agent falls into the slurry control tray 13 at the bottom of the slurry control bracket 20, and the bottom pipe of the slurry control tray 13 is connected to the first pneumatic pump valve 3.3 of the slurry supply pump 3.

[0037] The pre-drying system ④ is composed of a vacuum oven 23, a first constant volume grid assembly 22 and the slurry-pressed carbon fibers, wherein: the gas and moisture exhausted from the vacuum oven 23 are led to the outside through an exhaust pipe 23.1 and discharged into the air; the four movable pulleys of the vacuum negative pressure oven 23 are all equipped with a brush device.

[0038] The chopping system ⑤ consists of a cutter 26, a chopping collection bucket 30, a PC dust cover 25, and pre-dried regenerated carbon fibers 27. The dust generated during the chopping of the pre-dried regenerated carbon fibers 27 enters the dust collection system through the suction pipe (25.1) at the top of the PC dust cover 25.

[0039] The secondary drying system ⑥ consists of a hot air dryer 31 and chopped regenerated carbon fibers 32. The water vapor generated during the secondary drying process is discharged outdoors through an exhaust pipe 31.1 at the top of the hot air dryer 31; the four movable pulleys of the hot air dryer 31 are all equipped with brushes.

[0040] The exhaust (steam) and dust exhaust pipes of the pre-baking system ④, short-cut system ⑤ and secondary baking system ⑥ adopt carbon fiber reinforced plastic hoses with carbon fiber reinforced plastic flanges, and the connection method is carbon fiber reinforced plastic bolts and nuts and carbon fiber reinforced thermoplastic elastomer sealing gaskets.

[0041] The method for processing regenerated carbon fibers using the industrialized preparation device for chopped regenerated carbon fibers is characterized in that the method comprises the following steps:

[0042] 1) The sizing agent is in place: the first valve 5 of the slurry supply tank 2, the first pneumatic pump valve (3.3) and the fifth valve (3.2) on the right side of the slurry supply pump 3 are closed, the second valve (5.1) and the fourth valve (3.1) are opened, the slurry supply pump 3 is started to pump the sizing agent (8) into the slurry supply tank 2 for storage through the second valve (5.1), the second pneumatic pump valve (3.4) and the fourth valve (3.1), when the liquid level of the sizing agent (8) pumped into the slurry supply tank (2) reaches 80%, the second valve (5.1) is closed and the first valve (5) is opened to establish the self-circulation of the slurry supply tank 2, the agitator 1 is turned on, and the frequency conversion is adjusted to adjust the opening to 50% to keep the components of the sizing agent 8 uniform.

[0043] 2) Assembly and installation of regenerated carbon fiber: N pairs of concave column nets 7.4 and convex column nets 7.2 containing a certain amount of regenerated carbon fiber 9 to be sized are combined with corresponding concave columns 7.3 and convex columns 7.1, and the concave column nets 7.4 are horizontally flipped 180 degrees along the AB axis to form a first constant volume grid assembly 7. The first constant volume grid assembly 7 is moved into the sizing tank 4, and the bottoms of the two touch but are not fixed, where N is 4 to 10.

[0044] 3) Sizing of the recycled carbon fiber batches of the first constant volume grid assembly 7: open the fifth valve 3.2, close the fourth valve 3.1, and pass the sizing agent 8 in the sizing tank 2 through the sizing pump 3 and the sizing agent distribution pipe 10's co-directional nozzle 11, perpendicular to the left inner wall of the sizing tank 4, and collide with it. After turbulent mixing, it becomes laminar flow through reverse power and enters the first constant volume grid assembly 7 horizontally to soak the recycled carbon fiber. When the liquid level of the sizing tank 4 reaches 80%, close the second pneumatic pump valve 3.4, open the bottom valve 12 of the sizing tank 4 and the first pneumatic pump valve 3.3, and establish the sizing agent self-circulation of the sizing tank 4. Sizing process: The sizing tank 4 is immersed for 60±15 seconds. Take out the first constant volume grid assembly 7 after the immersion is completed, and enter the next batch of the first constant volume grid assembly 7 for sizing according to the above operation. When the liquid level of the sizing tank 4 is close to the top of the first constant volume grid assembly 7, the second pneumatic pump valve 3.4 is opened, and when the liquid level of the sizing tank 4 is replenished to 80%, the second pneumatic pump valve 3.4 is closed.

[0045] 4) Slurry control of recycled carbon fiber: take out the first constant volume grid assembly 7 from the sizing tank 4 and place it horizontally on the bottom horizontal steel shaft of the product clamping steel shaft 14 of the slurry control system ③, rotate each concave column grid 7.4 horizontally by 180 degrees, and reassemble it into a second constant volume grid assembly 18, starting from the grouting backboard 19 on the right side, in sequence towards the grouting plate 16, with the two fixed ports facing downward, and aligning and erecting it on the product clamping steel shaft 14 to the right side close to the grouting plate 16; gradually open and increase the compressed air, and control the pressure at 0.20-0.6Mpa. The sizing plate 16 is driven by compressed air and moves to the right. Under the back pressure of the sizing back plate 19, it squeezes the sized regenerated carbon fibers in the second constant volume grid assembly 18. At this time, the spacing between the concave column net 7.4 and the convex column net 7.2 moves from 2a to 1a, and the squeezing time is 80-120 seconds. The extruded sizing agent falls into the sizing control tray 13 under the bottom of the sizing control bracket 20. The third valve 13.1 of the sizing control tray 13 is opened to pump the sizing agent into the sizing tank 4 through the slurry supply pump 3. Stop the compressed air, take out the units of the second constant volume grid assembly 18 that have completed sizing control in turn, and transport them to the regenerated carbon fiber pre-baking process. After pre-baking, according to the above operation, enter the first constant volume grid assembly 7 after sizing for the next batch of sizing.

[0046] 5) Pre-baking of regenerated carbon fibers: Restore the second constant volume grid assembly 18 to the first constant volume grid assembly 7. Pre-baking process: operating temperature range 85±10°C; drying time 45±15 minutes; vacuum 30±15KPa.

[0047] 6) Chopping of regenerated carbon fibers: The cutter 26 is turned on, and the pre-baked regenerated carbon fibers are taken out and placed sequentially in the feed port of the cutter 26 for chopping. The chopped regenerated carbon fibers fall through the guide chute into the chopped material receiving barrel 30. Chopping process: Chopping frequency 120 ± 60 times / min, cutting length: 1-12 mm;

[0048] 7) Secondary drying of chopped regenerated carbon fibers: The chopped material receiving barrel 30 filled with regenerated carbon fibers is sent to a hot air dryer 31 for secondary drying.

[0049] 8) When the liquid level of the slurry supply tank 2 is lower than 20%, return to step 1), pump in the prepared sizing agent until the liquid level of the slurry supply tank 2 reaches 80%, and continue the subsequent production operations until the production task is completed.

[0050] 9) Equipment cleaning: After completing the production task, close the fifth valve 3.2, open the fourth valve 3.1, and pump all the slurry agents in the sizing system ② and the slurry control system ③ back to the slurry supply tank 2; stop the slurry supply pump 3 and the agitator 1, connect the sewage pipe outlet of the second valve 5.1 to a temporary plastic hose, and let the slurry agent in the slurry supply tank 2 flow into the raw material barrel by gravity pressure difference for storage and reuse next time. Close the third valve 13.1 and the fourth valve (3.1), open the fifth valve (3.2), and place the used concave column net and convex column net into the sizing tank (4) of the sizing system ②, and fill it with water to a liquid level of 90%, start the sizing pump (3) to establish the sizing system ② self-circulation, and clean the concave column net, convex column net and the sizing tank 4; after completing the sizing system ② cleaning, close the fifth valve (3.2), open the fourth valve (3.1), pump all the cleaning water of the sizing tank (4) into the sizing tank (2), close the sixth valve (12), open the third valve (13.1) and rinse the sizing control system ③ with a small amount of water. The left side of the grouting back plate 19, the right side of the grouting plate (16), the type clamping steel shaft (14) and the grouting control tray (13) are squeezed; after the grouting control system ③ is cleaned, all the cleaning water is pumped into the grouting tank (2), the third valve (13.1) and the first pneumatic pump valve (3.3) are closed, and the second pneumatic pump valve (3.4) and the agitator (1) are opened to establish the grouting tank (2) self-circulating cleaning; after the grouting system ① is cleaned, the grouting pump (3) and the agitator (1) are stopped, the second valve (5.1) is opened, and the cleaning sewage is discharged to the sewage treatment tank through a plastic hose or a bucket, and then all valves are closed.

[0051] The main structural functions of each system of the industrial production apparatus for chopped regenerated carbon fibers of the present invention are further described as follows in conjunction with the industrial production method for chopped regenerated carbon fibers:

[0052] Slurry supply system ① and its use method: The system is composed of a slurry supply tank 2 with a stirrer 1 and a slurry supply pump 3, see Figure 2 On the left, the stirring blade of the stirrer 1 is in the middle and lower part of the slurry supply tank 2, which is a metal blade type and is controlled by a frequency converter; the bottom of the slurry supply tank 2 is composed of a first valve 5 and a second valve (5.1) of the discharge pipe mouth, the second valve (5.1) is connected to the second pneumatic pump valve 3.4 on the left side of the inlet of the slurry supply pump 3, and the right side of the inlet of the slurry supply pump is connected to the first pneumatic pump valve (3.3) at the bottom of the slurry supply tank and the slurry control tank, the sixth valve (12) and the third valve (13.1); the fourth valve 3.1 on the left side of the outlet of the slurry supply pump 3 is connected to the reflux pipe mouth at the top of the slurry supply tank 2, and the fifth valve 3.2 on the right side is connected to the inlet of the sizing agent distribution pipe 10 erected on the left side of the slurry supply tank 4.

[0053] Sizing system ② and its use method: The system consists of a sizing tank 4, a sizing agent 8, a first constant volume grid assembly 7, recycled carbon fiber 9, and a sizing agent distribution pipe 10. The sizing system is shown in the attached Figure 2On the right, the first constant volume grid combination 7 is shown Figure 3 It is composed of N pairs of concave column nets 7.4 and convex column nets 7.2 with concave columns 7.3 and convex columns 7.1 fitted in reverse, wherein N is 4 to 10; the regenerated carbon fibers 9 are quantitatively and orderly confined in the first constant volume grid assembly 7; the first constant volume grid assembly 7 is horizontally immersed and placed on the bottom of the sizing tank 4 by its own weight; the sizing agent distribution pipe (10) is located between the left side of the first constant volume grid assembly 7 and the left inner wall of the sizing tank 4, and is fixed in a vertical manner in the clamp at the right end of the two brackets welded on the upper and lower inner wall of the left side of the sizing tank 4; the sizing agent distribution pipe 10 is evenly distributed with a row of unidirectional nozzles 11 along the axial direction, and the nozzles 11 are perpendicular to the left inner wall of the sizing tank 4; the bottom right side of the sizing tank 4 has a discharge pipe opening, and the discharge pipe opening is connected to the right pipe opening of the slurry supply pump 3 through the sixth valve 12 and the pipeline with a metal pipe flange.

[0054] During the production process, under room temperature, the slurry supply pump 3 supplies slurry to the sizing tank 4 on its right side. The sizing agent 8 is sprayed 11 toward the left inner wall of the sizing tank 4 through a row of sizing agent distribution pipes (10) to reduce the impact force, and then flows horizontally in the reverse direction through each layer of regenerated carbon fiber in the first constant volume grid assembly 7, and then passes through the sixth valve 12 on the right side of the bottom of the sizing tank 4 and the slurry supply pump 3 to self-circulate for 60±15 seconds. The regenerated carbon fiber 9 is uniformly and quantitatively sized in the first constant volume grid assembly 7.

[0055] Slurry control system ③ and its use method: the system consists of a type clamping steel shaft 14, a grouting plate 16, a second constant volume grid assembly 18, a grouting back plate 19, a slurry control bracket 20 and a slurry control tray 13: wherein the type clamping steel shaft 14 consists of an upper clamping shaft and two lower supporting shafts, the left and right ends of the upper clamping shaft are respectively fixed to the middle of the left and right sides of the top of the slurry control bracket 20 from the outside to the inside, and the left and right ends of the two lower supporting shafts are respectively fixed to the The grouting support 20 is on the bottom crossbeam from outside to inside at the left and right sides; the grouting plate 16 is made of light alloy steel, and its plate size is the same as the size and shape of the end face of the constant volume grid. Its grouting power is driven by compressed air, and the compressed air high-pressure hose is respectively connected to the compressed air 17 in the middle and upper part of the grouting plate and the sealing short section 15 at the lower part with a metal quick connector; the upper, middle and lower parts of the right side of the grouting back plate 19 are respectively welded to the middle of the upper, middle and lower crossbeams on the right side of the grouting support 20. The grouting plate 16 moves from left to right under the drive of compressed air to squeeze the sized recycled carbon fiber in the second constant volume grid assembly 18; the extruded sizing agent falls into the grouting tray 13 at the bottom of the grouting support 20, and the bottom pipe of the grouting tray 13 is connected to the first pneumatic pump valve 3.3 of the slurry supply pump 3.

[0056] After the sizing is completed, the first constant volume grid assembly 7 is taken out from the sizing tank 4, and each concave column grid is rotated 1800 degrees horizontally. Figure 4 Reassemble into the second constant volume grid assembly 18 and place it upright on the product clamping steel shaft 14 and between the grouting plate 16 and the grouting back plate 19. Figure 5 The compressed air is turned on and the pressure is controlled at 0.10-0.20 MPa. The sizing plate 16 moves to the right under the drive of the compressed air and squeezes the sized recycled carbon fibers in the second constant volume grid assembly 18 under the back pressure of the sizing back plate 19. The squeezed sizing agent 8 falls into the sizing control tray 13 at the bottom of the sizing control bracket 20 and is then pumped into the sizing tank 4 through the sizing pump 3.

[0057] Pre-drying system ④ and its use: The pre-drying system consists of a low-temperature vacuum oven 23 and a horizontally positioned second constant-volume grid assembly 18, which has been completed after slurry control. The second constant-volume grid assembly 18 is arranged in the same configuration as the first constant-volume grid assembly 7 to increase the drying area and improve drying efficiency. Pre-drying process: operating temperature range 85±10°C; drying time 45±15 minutes; vacuum 30±15 kPa.

[0058] ⑤Chopping system and its use: The chopping system consists of recycled carbon fiber 27, a cutting machine 26, a chopped material collection barrel 30, and a dust cover 25 (material: PC). The cutting method is guillotine-type, and the blade material is R:CrMo steel, chromium-molybdenum powder metallurgy, hardened or YNG151 reinforced ceramic. The collection barrel is made of 304.

[0059] Short cutting process: continuous cutting, cutting frequency 120±60 times / min, cutting length: 3-12MM.

[0060] ⑥ Secondary drying system and its use: The secondary drying system consists of a high-temperature oven and a pre-drying chopped material collection drum. The secondary drying process varies depending on the sizing agent brand. For PI sizing agents: bake at 160-180°C for 60-80 minutes, then 230-240°C for 20-30 minutes. For high-temperature PA, PU, ​​and polyphenolic sizing agents: bake at 160-180°C for 60-80 minutes. For standard PP, PU, ​​PA, or conventional thermosetting sizing agents, bake at 100-120°C for 100-120 minutes.

[0061] Example 1

[0062] The short-cut regenerated carbon fiber industrial preparation device and its use method of the present invention are composed of six parts: slurry supply ① sizing ② slurry control ③ pre-drying ④ short-cutting ⑤ secondary drying ⑥ (see Figure 1In order to facilitate the operation of the device and the comparison of the effect, 5 groups of 1000g fixed volume (or fixed quantity) grid recycled carbon fibers were sequentially sized with thermoplastic 5.5% PI sizing agent, sizing control, pre-baking, short cutting and secondary baking to form the recycled carbon fiber products. The particle uniformity, sizing uniformity, bulk density (0.55g / cm 3 ) and the implementation effect of continuous measurement performance evaluation.

[0063] The implementation steps are as follows:

[0064] 1) Sizing agent in place: see Figure 2 , use the slurry supply pump (3) to pump 5.5% PI into the slurry supply tank (2) through the second valve 5.1 for storage. When the liquid level reaches 80%, close the second valve 5.1, establish the slurry supply tank (2) self-circulation, turn on the agitator 1, and adjust the opening to 50% through frequency conversion to keep the sizing agent components uniform.

[0065] 2) Fixed volume and combined installation of recycled carbon fiber: 5 groups of 2000 g / group fixed volume (or fixed shape and quantity) grids totaling 10 kg of recycled carbon fiber are reassembled into 10 groups of 1000 g / group combinations (defined as the first fixed volume grid 7, the same below). The first fixed volume grid 7 consists of 10 pairs of concave column grids 7.4 and convex column grids (7.2) containing recycled carbon fiber, which are matched with corresponding concave columns 7.3 and convex columns 7.1 (see Figure 3 The regenerated carbon fibers 9 are limited in space during sizing by the first constant volume grid 7. The first constant volume grid 7 is moved into the sizing tank 4, and the bottoms of the two touch each other but are not fixed.

[0066] 3) Sizing of the first constant volume grid 7: see the sizing process Figure 2 . The sizing agent in the sizing tank 2 is self-circulated and cut to the sizing tank 4 through the sizing pump 3, so that the sizing agent immerses the first constant volume type grid 7. When the liquid level of the sizing tank 4 reaches 80%, the feeding is stopped, and the sixth valve 12 on the right side of the bottom of the sizing tank 4 is connected to the right side pipe mouth of the tee of the sizing pump inlet 6 with a third metal pipe flange; the outlet of the sizing pump 3 is connected to the inlet 10 of the sizing agent distribution pipe with a second metal pipe flange; and the self-circulation of the sizing tank 4 is established. The sizing agent 8 passes through the sizing agent distribution pipe 10 in the same direction nozzle 11, collides perpendicularly with the left inner wall of the sizing tank 4, and after turbulent mixing, it becomes laminar flow through reverse power, enters the first constant volume type grid 7 horizontally, and impregnates the regenerated carbon fiber.

[0067] 4) Second constant volume grid assembly 16 constant volume, combined installation: constant volume assembly and slurry control process are shown in Figure 4 , Figure 5 Take out the first constant volume grid assembly 7 from the sizing tank 4, rotate each concave column grid 180 degrees horizontally, and press Figure 4Reassemble into the second constant volume grid assembly, and place it on the product clamping steel shaft 14 and between the grouting plate 16 and the grouting back plate 19. Turn on the compressed air, and control the pressure at 0.20Mpa. Driven by the compressed air 17, the grouting plate 16 moves to the right. Under the back pressure of the grouting back plate 19, the sizing regenerated carbon fiber in the second constant volume grid assembly 18 is squeezed. At this time, the spacing between the concave column network 7.4 and the convex column network 7.2 moves from 2a to 1a, as shown. Figure 6 The extruded sizing agent strategically falls into the sizing control tray 13 at the bottom of the sizing control bracket 20, and the sizing agent is then pumped into the sizing tank 4 through the sizing pump 3.

[0068] 5) Pre-drying of Sized Recycled Carbon Fibers: Return the second constant-volume grid assembly 18 to the first constant-volume grid assembly 7 to increase the drying area and improve drying efficiency. Pre-drying process: Operating temperature 95°C; drying time 60 minutes; vacuum 25 kPa.

[0069] 6) Pre-baked regenerated carbon fiber chopped: The cutter 26 is operated, and the pre-baked regenerated carbon fiber is removed and placed in the cutter feed port in sequence for chopped. The chopped carbon fiber falls into the chopped material receiving bucket 30 through the guide chute. Chopped process: Continuous chopping, 180 cuts / min, 6mm cut length.

[0070] 7) Second drying of chopped recycled carbon fiber: The chopped receiving barrel 30 filled with chopped carbon fiber is sent to the second drying oven. Because of the PI type sizing agent, the drying process is set as: 180°C for 60 minutes and 235°C for 30 minutes.

[0071] 8) Finished product quality inspection: The particle uniformity, sizing rate uniformity, bulk density and continuous metering performance of the chopped recycled carbon fiber twin-screw of the second drying were tested. The results are shown in the effect comparison table Example 1 test results.

[0072] Example 2 to Example 7

[0073] The present invention employs an industrialized production apparatus and method for chopped recycled carbon fibers. To facilitate operation and comparison of results, five groups of 1000-gram fixed-volume (or fixed-size and fixed-quantity) grid-regenerated carbon fibers were sequentially subjected to thermoplastic PI sizing, sizing control, pre-baking, chopped, secondary baking, and twin-screw metering. Each new embodiment differs from Example 1 by only one condition; see the Effect Comparison Table for specific test conditions. The results of the implementation were evaluated based on the finished product's particle uniformity, sizing uniformity, bulk density, and continuous metering performance. See the corresponding test results in the Effect Comparison Table.

[0074] Example 8 to Example 11

[0075] The present invention employs an industrialized production apparatus and method for chopped regenerated carbon fibers. To facilitate operation and comparison of results, five groups of 1000-gram fixed-volume (or fixed-size and fixed-quantity) grid-regenerated carbon fibers were sequentially sized with a thermoplastic and thermosetting sizing agent, sizing control, pre-baking, chopped, double-baked, and metered using a twin-screw extruder. Each product was tested using the conditions of Example 7. See the Effect Comparison Table for specific test conditions. The results of the implementation were evaluated based on the finished product's particle uniformity, sizing uniformity, bulk density, and continuous metering performance. See the corresponding test results in the Effect Comparison Table.

[0076] Comparative Examples 1 to 6

[0077] The present invention is used to prepare short-cut recycled carbon fibers for industrial use and to compare their operation. Five groups of 1000-gram fixed-volume (or fixed-size) grid-regenerated carbon fibers were sequentially sized with thermoplastic and thermosetting sizing agents, sizing control, pre-baking, chopped, double-baking, and twin-screw metering. Each comparative example deviated one condition from Example 7. See the Effect Comparison Table for specific test conditions. The results of the implementation were evaluated based on the particle uniformity, sizing uniformity, bulk density, and continuous metering performance of the finished product. See the corresponding test results in the Effect Comparison Table.

[0078] From the above comparison, it can be seen that the chopped RCF produced using the disclosed apparatus and method for industrial production of chopped recycled carbon fibers, regardless of whether the sizing agent is a thermoplastic, thermosetting, or composite sizing agent, exhibits excellent particle and sizing uniformity, bulk density, and continuous, precise metering. This opens a new avenue for the application of RCF in the RCFTP field. Furthermore, the present invention boasts high production efficiency, ease of operation, safety, and environmental friendliness, making it suitable for the industrial production of chopped recycled carbon fibers with thermoplastic and thermosetting sizing agents.

[0079] Table 1. Comparison of the effects of the embodiments

[0080]

[0081] Note: √: qualified; √√: good; √√√: excellent; ×: unqualified; ××: poor; ×××: very poor.

Claims

1. An industrial preparation device for chopped recycled carbon fibers, characterized in that The device consists of a slurry supply system ①, a sizing system ②, a slurry control system ③, a pre-drying system ④, a short-cut system ⑤ and a secondary drying system ⑥, wherein: the slurry supply system ①, the sizing system ②, and the slurry control system ③ are in one space, and are fixed to the horizontal ground by metal anchor bolts from left to right in the process flow of industrial equipment, with an interval of 2-3 meters; the pre-drying system ④ and the secondary drying system ⑥ can be moved. According to the production scale and production rhythm, they can be located on the right side of the slurry control system ③, arranged left and right according to the process flow, and locked to the horizontal ground by their respective mobile roller brushes, with a distance of 2-3 meters. They can also be moved to a special drying function space, and the two devices are placed on the left and right, with a distance of 1-2 meters; and the short-cut system ⑤ is in an independent carbon fiber cutting space with a dust exhaust device, and is fixed to the horizontal ground by metal anchor bolts; The slurry supply system ① is composed of an agitator (1), a slurry supply tank (2) and a slurry supply pump (3): the stirring blade of the agitator (1) is located in the middle and lower part of the slurry supply tank (2), is a metal blade type, and is controlled by a frequency converter; the slurry supply pump (3) is a carbon fiber reinforced PPS pneumatic pump, located on the ground in the middle between the slurry supply tank (2) and the upper slurry tank (4), and is fixed to the ground with metal bolts; the bottom of the slurry supply tank (2) is composed of a first valve (5) and a second valve (5.1) for the discharge pipe, and the first valve (5.2) and the second valve (5.3) for the discharge pipe are connected to the slurry supply tank (2). The second valve (5.1) is connected to the second pneumatic pump valve (3.4) on the left side of the inlet of the slurry supply pump (3), and the right side of the inlet of the slurry supply pump is connected to the first pneumatic pump valve (3.3) at the bottom of the slurry supply tank and the slurry control tank, and the sixth valve (12) is connected to the third valve (13.1); the fourth valve (3.1) on the left side of the outlet of the slurry supply pump (3) is connected to the return pipe port at the top of the slurry supply tank (2), and the fifth valve (3.2) on the right side is connected to the inlet of the sizing agent distribution pipe (10) erected on the left side in the slurry supply tank (4); The sizing system ② is composed of a first constant volume grid assembly (7), a sizing tank (4), a sizing agent (8), a regenerated carbon fiber (9) and a sizing agent distribution pipe (10): wherein the first constant volume grid assembly (7) is composed of N pairs of concave column nets (7.4) and convex column nets (7.2) with concave columns (7.3) and convex columns (7.1) fitted in reverse, wherein N is 4 to 10; the regenerated carbon fiber (9) is quantitatively and orderly confined in the first constant volume grid assembly (7); the first constant volume grid assembly (7) is horizontally immersed and placed at the bottom of the sizing tank (4) by its own weight; the The sizing agent distribution pipe (10) is located between the left side of the constant volume grid assembly (7) and the left inner wall of the sizing tank (4), and is fixed in a vertical manner in the clamp at the right end of the two brackets welded on the upper and lower inner walls of the left inner wall of the sizing tank (4); the sizing agent distribution pipe (10) is evenly distributed in a row of unidirectional nozzles (11) along the axial direction, and the nozzles (11) are perpendicular to the left inner wall of the sizing tank (4); the bottom right side of the sizing tank (4) has a discharge pipe opening, and the discharge pipe opening is connected to the right pipe opening of the slurry supply pump (3) through a sixth valve (12) and a pipeline with a metal pipe flange; The grouting control system ③ is composed of a type clamping steel shaft (14), a grouting plate (16), a second constant volume grid assembly (18), a grouting back plate (19), a grouting support (20) and a grouting tray (13): wherein the type clamping steel shaft (14) is composed of an upper clamping shaft and two lower supporting shafts, the left and right ends of the upper clamping shaft are respectively fixed by bolts to the middle of the left and right sides of the top of the grouting support (20) from the outside to the inside, and the left and right ends of the two lower supporting shafts are respectively fixed by bolts to the left and right sides of the bottom crossbeam of the lower part of the grouting support (20) from the outside to the inside; the grouting plate (16) is made of light alloy steel, and its plate surface size is the same as the size and shape of the end face of the constant volume grid, and its grouting dynamic The force is driven by compressed air, and the compressed air high-pressure hose is respectively connected to the compressed air (17) in the middle and upper part of the grouting plate and the sealing short section (15) at the lower part by a metal quick connector; the upper, middle and lower parts of the right side of the grouting back plate (19) are respectively welded to the middle parts of the upper, middle and lower cross beams on the right side of the grouting control bracket (20); the grouting plate (16) is driven by the compressed air (17) to move from left to right to squeeze the sized recycled carbon fiber in the second constant volume grid assembly (18); the extruded sizing agent falls into the grouting control tray (13) at the bottom of the grouting control bracket (20), and the bottom pipe of the grouting control tray (13) is connected to the first pneumatic pump valve (3.3) of the slurry supply pump (3); The pre-drying system ④ is composed of a vacuum oven (23), a first constant volume grid assembly (7) and the carbon fibers after slurrying, wherein: the gas and moisture discharged from the vacuum oven (23) are led to the outside through the exhaust pipe (23.1) and discharged at high altitude; the four movable pulleys of the vacuum oven (23) are all equipped with a brush device; The short-cutting system ⑤ is composed of a cutting machine (26), a short-cutting material collecting barrel (30), a PC dust cover (25), and a pre-baked regenerated carbon fiber (27); dust generated during the short-cutting process of the pre-baked regenerated carbon fiber (27) enters the dust collection system through the suction pipe (25.1) on the top of the PC dust cover (25); The secondary drying system ⑥ is composed of a hot air dryer (31) and short-cut recycled carbon fibers (32); the water vapor generated during the secondary drying process is discharged outdoors at high altitude through the exhaust pipe (31.1) on the top of the hot air dryer (31); the four movable pulleys of the hot air dryer (31) are all equipped with a brush device; The exhaust (steam) and dust exhaust pipes of the pre-baking system ④, the short-cut system ⑤ and the secondary baking system ⑥ adopt carbon fiber reinforced plastic hoses with carbon fiber reinforced plastic flanges, and the connection method is carbon fiber reinforced plastic bolts and nuts and carbon fiber reinforced thermoplastic elastomer sealing gaskets.

2. A method for preparing regenerated carbon fibers using the industrialized preparation device for chopped regenerated carbon fibers according to claim 1, characterized in that: The method comprises the following steps: 1) The sizing agent is in place: the first valve (5) of the slurry supply tank (2), the first pneumatic pump valve (3.3) and the fifth valve (3.2) on the right side of the slurry supply pump (3) are closed, the second valve (5.1) and the fourth valve (3.1) are opened, the slurry supply pump (3) is started, and the sizing agent (8) is pumped into the slurry supply tank (2) for storage through the second valve (5.1), the second pneumatic pump valve (3.4) and the fourth valve (3.1). When the liquid level of the sizing agent (8) pumped into the slurry supply tank (2) reaches 80%, the second valve (5.1) is closed and the first valve (5) is opened to establish the self-circulation of the slurry supply tank (2), the agitator (1) is opened, and the frequency conversion is adjusted to adjust the opening to 50% to keep the components of the sizing agent (8) uniform; 2) Assembly and installation of regenerated carbon fiber: N pairs of concave column nets (7.4) and convex column nets (7.2) containing a certain amount of regenerated carbon fiber (9) to be sized are formed with corresponding (7.3) concave columns and (7.1) convex columns, and the concave column nets (7.4) are horizontally turned 180 degrees along the AB axis to form a first constant volume grid assembly (7), and the first constant volume grid assembly (7) is moved into the sizing tank (4), with the bottoms of the two touching but not fixed, wherein N is 4 to 10; 3) Batch sizing of the regenerated carbon fibers in the first constant volume grid assembly (7): Open the fifth valve (3.2), close the fourth valve (3.1), and pass the sizing agent (8) in the sizing tank (2) through the sizing pump (3) and the sizing agent distribution pipe (10) in the same direction nozzle (11), perpendicular to the left inner wall of the sizing tank (4), and collide with it. After turbulent mixing, it becomes laminar flow through reverse power and enters the first constant volume grid assembly (7) horizontally to soak the regenerated carbon fibers. When the liquid level in the sizing tank (4) reaches 80%, close the second pneumatic pump valve (3.4). ), open the sixth valve (12) of the sizing tank (4) and the first pneumatic pump valve (3.3), and establish the sizing agent self-circulation of the sizing tank (4); sizing process: the sizing tank (4) is immersed for 60±15 seconds, and the first constant volume grid assembly (7) after the immersion is completed is taken out, and the next batch of the first constant volume grid assembly (7) is sizing according to the above operation; when the liquid level of the sizing tank (4) is close to the top of the first constant volume grid assembly (7), the second pneumatic pump valve (3.4) is opened, and the second pneumatic pump valve (3.4) is closed when the liquid level of the sizing tank (4) is replenished to 80%; 4) Regenerated carbon fiber slurry control: Take out the first constant volume grid assembly (7) from the slurry tank (4) and place it horizontally on the bottom horizontal steel shaft of the type clamping steel shaft (14) of the slurry control system ③, rotate each concave column grid (7.4) horizontally by 180 degrees, and reassemble it into the second constant volume grid assembly (18), starting from the right side grouting back plate (19), in turn towards the grouting plate 16, with the two fixed ports facing downward, and align and erect it on the type clamping steel shaft (14) to the right side of the grouting plate 16; gradually open the compressed air and control the pressure at 0.20 --0.6Mpa; the sizing plate (16) is driven by compressed air and moves to the right. Under the back pressure of the sizing back plate 19, the sizing regenerated carbon fibers in the second constant volume grid assembly (18) are squeezed. At this time, the spacing between the concave column net (7.4) and the convex column net (7.2) moves from 2a to 1a, and the squeezing time is 80-120 seconds; the squeezed sizing agent falls into the sizing control tray (13) under the bottom of the sizing control bracket (20), and the third valve (13.1) of the sizing control tray (13) is opened to pump the sizing agent into the sizing tank (4) through the slurry supply pump (3); the compressed air is stopped, and the second constant volume grid assembly (18) units that have completed sizing are taken out in turn and transported to the regenerated carbon fiber pre-baking process. After pre-baking, the first constant volume grid assembly (7) after sizing of the next batch is entered according to the above operation; 5) Pre-baking of recycled carbon fiber: restore the second constant volume grid assembly (18) to the first constant volume grid assembly (7); pre-baking process: operating temperature range 85±10°C; drying time 45±15min; vacuum 30±15 KPa; 6) Chopping the regenerated carbon fiber: start the cutting machine (26), take out the pre-baked regenerated carbon fiber, and place it in the feed port of the cutting machine (26) in sequence for cutting. The cut regenerated carbon fiber falls into the chopped material receiving barrel (30) through the guide trough. The chopping process: cutting frequency 120±60 times / min, cutting length: 1-12MM; 7) Second drying of chopped recycled carbon fibers: the chopped receiving barrel (30) filled with recycled carbon fibers is sent to a hot air dryer (31) for secondary drying; 8) When the liquid level of the slurry supply tank (2) is lower than 20%, return to step 1), pump in the prepared sizing agent until the liquid level of the slurry supply tank (2) reaches 80%, and continue the subsequent production operations until the production task is completed; 9) Cleaning of the device: After completing the production task, close the fifth valve (3.2), open the fourth valve (3.1), and pump all the slurry in the sizing system ② and the sizing control system ③ back to the sizing tank (2); stop the sizing pump (3), the agitator (1), and connect the sewage outlet of the second valve (5.1) to a temporary plastic hose, so that the sizing agent in the sizing tank (2) flows into the raw material barrel by gravity pressure difference for storage and reuse next time; close the third valve (13.1) and the fourth valve (3.1), open the fifth valve (3.2), and put the used concave column net and convex column net into the sizing tank (4) of the sizing system ②, and fill it with water to 90%, open the sizing pump (3) to establish the sizing system ② self-circulation, and clean the concave column net, convex column net and sizing tank (4); after completing the cleaning of the sizing system ②, close the fifth valve (3.2) ), open the fourth valve (3.1), pump all the cleaning water of the sizing tank (4) into the sizing tank (2), close the sixth valve (12), open the third valve (13.1) and use a small amount of water to rinse the left side of the grouting back plate 19 of the sizing control system ③, the right side of the grouting plate (16), the type clamping steel shaft (14) and the sizing control tray (13); after completing the cleaning of the sizing control system ③, after all the cleaning water is pumped into the sizing tank (2), close the third valve (13.1) and the first pneumatic pump valve (3.3), open the second pneumatic pump valve (3.4) and the agitator (1), and establish the self-circulating cleaning of the sizing tank (2); after completing the cleaning of the sizing system ①, stop the sizing pump (3) and the agitator (1), open the second valve (5.1), discharge the cleaning sewage to the sewage treatment tank through a plastic hose or a bucket, and close all valves.

3. The method for preparing chopped regenerated carbon fibers according to claim 2, wherein: The sizing agents include PI, PA, PU and polyphenolic high temperature sizing agents.

4. The method for preparing chopped regenerated carbon fibers according to claim 2, wherein: The two-drying process varies according to the brand of sizing agent: for PI sizing agent: bake at 160-180℃ for 60-80min, bake at 230-240℃ for 20-30min; for high-temperature PA, PU and polyphenolic sizing agents: bake at 160-180℃ for 60-80min; for ordinary PP, PU and PA, bake at 100-120℃ for 100-120min.

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