Recycling methods for continuous fiber reinforced thermoplastic 3D printed composites

Abstract

The present invention discloses a method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials. The method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials includes fixing the composite materials to be recycled to the bottom of a horizontal support plate, and setting a material receiving trough below the composite materials; moving the heating head to contact the lower surface of the composite materials, and using a mechanical arm to drive the heating head to move in the opposite direction of the composite materials 3D printing, the heating head melts the resin matrix, and using a traction mechanism to peel off the fibers in the melting area of ​​the resin matrix, and the melted resin matrix falls downward into the material receiving trough. The present invention realizes the recycling of part of the resin matrix, improves the recycling benefits of waste continuous fiber reinforced thermoplastic 3D printing composite materials, and also improves the recycling efficiency, and the economic benefits are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber composite material recycling, and in particular to a method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials. Background Art

[0002] Continuous fiber reinforced thermoplastic composites are based on thermoplastic resins and have high damage tolerance, excellent mechanical properties, thermal properties and corrosion resistance. They have become a hot topic in the research of composite materials and are widely used in high-end fields such as aerospace, rail transportation, military industry, and entertainment and leisure. The traditional preparation method of continuous fiber reinforced thermoplastic composites is mainly lamination-hot pressing technology. The emergence of 3D printing technology provides a process that can realize the automation of composite products to a high degree for the molding and processing of continuous fiber reinforced thermoplastic composites. The 3D printing technology of continuous fiber reinforced thermoplastic composites not only has the characteristics of being able to mold complex composite products and high efficiency, but also can achieve customized mechanical properties. Therefore, 3D printing technology has also received extensive attention and research. However, with the development of 3D printing technology of continuous fiber reinforced thermoplastic composites and the composite materials industry, a large amount of composite waste is generated every year. The discarded composite products not only pose a serious threat to the natural environment, but also a large amount of fibers in the composite materials, especially expensive carbon fibers and some high-performance thermoplastic special engineering plastics, are difficult to recycle, which makes the development of composite materials encounter bottlenecks.

[0003] Common recycling methods for composite materials are mainly pyrolysis, crushing and incineration. All three methods do not meet the environmental requirements of energy conservation and emission reduction, and cannot achieve the recycling and reuse of printing filaments in composite materials. Therefore, it is crucial to develop a new recycling method for waste continuous fiber reinforced thermoplastic composite materials, reduce the cost of 3D printing technology, achieve efficient recycling of continuous fiber reinforced thermoplastic composite materials, ensure the performance of recycled continuous fiber printing filaments, reduce the pollution of waste 3D printed composite parts to the environment, and achieve the recycling of continuous fiber printing filaments for the sustainable development of the composite materials industry.

[0004] At present, the main challenges faced by the recycling technology of continuous fiber reinforced thermoplastic 3D printing composite materials are: the development and research of new recycling equipment and recycling processes; the recycled fiber printing filaments are damaged during the recycling process and cannot meet the requirements of re-printing; the traditional pyrolysis and combustion methods will produce a large amount of harmful gases during the recycling process, causing secondary pollution.

[0005] CN201610397940.8 discloses a 3D printed continuous fiber reinforced composite material recycling and remanufacturing method, which uses a hot air gun to move in the opposite direction of the 3D printing path of the composite material to heat the resin matrix to melt, thereby extracting the fibers. This method of hot air gun generally starts heating from the upper layer of the composite material. After the fibers are stripped off, part of the resin matrix stays on the top of the composite material and re-solidifies, resulting in a gradual increase in the thickness of the resin matrix on the top of the composite material, a gradual decrease in the fiber stripping efficiency, and a gradual increase in energy consumption. Summary of the invention

[0006] The object of the present invention is to provide a method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials, which improves the fiber stripping efficiency without increasing energy consumption and can recycle resin matrix materials.

[0007] The object of the present invention is achieved as follows: a method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials, fixing the composite materials to be recycled at the bottom of a horizontal support plate, and providing a material receiving trough below the composite materials;

[0008] Move the heating head to contact the lower surface of the composite material, use the robotic arm to drive the heating head to move in the opposite direction of the composite material 3D printing, the heating head melts the resin matrix, and use the traction mechanism to peel off the fibers in the melted area of ​​the resin matrix, and the melted resin matrix falls down into the receiving trough.

[0009] Furthermore, the traction mechanism comprises a recovery roller, a forming die and a guide roller, and the fiber is wound around the recovery roller after passing through the guide roller and the forming die in sequence.

[0010] Furthermore, the composite material to be recycled is fixed to the lower surface of the horizontal support plate by a clamping mechanism, the clamping mechanism includes a vertical first clamping plate, a vertical second clamping plate, a first fixing frame and a second fixing frame, the first clamping plate and the second clamping plate are parallel to each other, a clamping cavity is formed between the first clamping plate and the second clamping plate, the upper ends of the first clamping plate and the second clamping plate are slidably connected to the horizontal support plate, the first fixing frame is provided with a first push rod threadedly connected to the first fixing frame, the second fixing frame is provided with a second push rod threadedly connected to the second fixing frame, the end of the first push rod contacts the first clamping plate, and the end of the second push rod contacts the second clamping plate;

[0011] When fixing the composite material, put the composite material into the clamping cavity, rotate the first push rod and the second push rod, push the first clamping plate and the second clamping plate toward the composite material until the first clamping plate and the second clamping plate press the two sides of the composite material.

[0012] Furthermore, anti-slip bosses are provided on the clamping surfaces of the first clamping plate and the second clamping plate.

[0013] Furthermore, a tungsten slurry heater is arranged inside the heating head.

[0014] Furthermore, a temperature sensor and a pressure sensor are provided on the heating head.

[0015] Furthermore, during recycling, the heating head is inserted between the bottom layer of fibers and the penultimate layer of fibers of the composite material, and then moved in the opposite direction of the composite material 3D printing to melt the resin matrix outside the bottom layer of fibers and peel off the bottom layer of fibers.

[0016] The beneficial effects of the present invention are as follows: the present invention fixes the composite material to be recycled on the lower surface of the horizontal support plate, and during recycling, the fibers of the composite material to be recycled are stripped from bottom to top, and the melted resin matrix material drips into the receiving trough below under the action of gravity, preventing the resin matrix from accumulating on the surface of the composite material to be recycled and causing the thickness of the resin matrix to gradually increase, and the power of the heating head can be kept stable, avoiding increased energy consumption, and at the same time not affecting the stripping efficiency of the fibers. In addition, part of the resin matrix can also be recycled and reused, thereby improving the recycling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an overall schematic diagram of the present invention;

[0018] Figure 2 yes Figure 1 Schematic cross-sectional view of AA in the figure;

[0019] Figure 3 It is a schematic diagram of a heating head of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0021] The method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials of the present invention fixes the composite material 1 to be recycled on the lower surface of a horizontal support plate 2, and arranges a material receiving trough 3 below the composite material 1;

[0022] The heating head 5 is moved to contact the bottom of the composite material 1, and the robotic arm 4 is used to drive the heating head 5 to move in the opposite direction of the 3D printing of the composite material 1. The heating head 5 melts the resin matrix, and the fibers 6 in the melted area of ​​the resin matrix are peeled off by the traction mechanism, and the melted resin matrix falls downward into the receiving trough 3.

[0023] like Figure 1As shown, the horizontal support plate 2 is made of a metal plate with a certain thickness and is installed on a bracket so that the horizontal support plate 2 is at a suitable height. The receiving trough 3 is naturally placed below the horizontal support plate 2 to receive the dripping molten resin matrix. The receiving trough 3 is made of a metal material such as aluminum alloy and can withstand a certain high temperature. The mechanical arm 4 can be an existing commonly used mechanical arm, which can move within a certain range of three-dimensional space, thereby driving the heating head 5 to move in the opposite direction of the composite material 13D printing.

[0024] The heating head 5 can be an electric heating head with an electric heating wire arranged inside. Figure 3 As shown, a tungsten slurry heater 15 is provided inside the heating head 5. The tungsten slurry heater 15 generates high temperature after being powered on, and can melt the resin matrix. In order to facilitate the control of the heating temperature of the tungsten slurry heater 15 for melting different resin matrices, a temperature sensor 16 is provided on the heating head 5.

[0025] The traction mechanism is used to pull the fiber 6 so that the fiber 6 is peeled off from the composite material 1. The traction mechanism specifically includes a recovery roller 7, a molding die 8 and a guide roller 19. The fiber 6 passes through the guide roller 19 and the molding die 8 in turn and is wound on the recovery roller 7. The recovery roller 7 rotates driven by a motor and other equipment, thereby pulling the fiber 6 to reel in and providing power for the fiber 6 to be peeled off. The molding die 8 has a channel for the fiber 6 to pass through and a heating mechanism inside. When the fiber 6 passes through the channel, the resin matrix remaining on the fiber 6 melts and is scraped off. A container for receiving the resin matrix can also be set below the molding die 8. The scraped resin matrix flows along the channel to the channel mouth and drips into the container, further realizing the recovery of the resin matrix. The guide roller 19 is used for steering the fiber 6 so that the fiber 6 moves along the set direction.

[0026] The composite material 1 to be recycled is fixed to the lower surface of the horizontal support plate 2 by a clamping mechanism, such as Figure 2 As shown, the clamping mechanism includes a vertical first clamping plate 9, a vertical second clamping plate 10, a first fixing frame 11 and a second fixing frame 12, the first clamping plate 9 and the second clamping plate 10 are parallel to each other, a clamping cavity is formed between the first clamping plate 9 and the second clamping plate 10, the upper ends of the first clamping plate 9 and the second clamping plate 10 are slidably connected to the horizontal support plate 2, the first fixing frame 11 is provided with a first push rod 13 threadedly connected to the first fixing frame 11, the second fixing frame 12 is provided with a second push rod 14 threadedly connected to the second fixing frame 12, the end of the first push rod 13 contacts the first clamping plate 9, and the end of the second push rod 14 contacts the second clamping plate 10;

[0027] When fixing the composite material 1, put the composite material 1 into the clamping cavity, rotate the first push rod 13 and the second push rod 14, and push the first clamp plate 9 and the second clamp plate 10 toward the composite material 1 until the first clamp plate 9 and the second clamp plate 10 press the two sides of the composite material 1. There are four first push rods 13 and four second push rods 14, which can ensure sufficient clamping force. A dovetail-shaped slider can be provided at the upper end of the first clamp plate 9 and the second clamp plate 10, and a dovetail-shaped slide groove can be provided on the lower surface of the horizontal support plate 2, and the slider and the slide groove can be slidably matched. The clamping surfaces of the first clamp plate 9 and the second clamp plate 10 are provided with anti-slip bosses, which can improve the stability of the composite material 1.

[0028] The prior art only uses the heat of hot air to melt the resin matrix, and does not provide a force to promote the peeling of the fibers 6, so the efficiency is relatively low. In order to improve the peeling efficiency, when recycling, the heating head 5 is first inserted between the bottom layer of fibers 6 and the second to last layer of fibers 6 of the composite material 1, and then moves in the opposite direction of the 3D printing of the composite material 1 to melt the resin matrix outside the bottom layer of fibers 6 and peel off the bottom layer of fibers 6. After the bottom layer of fibers 6 is peeled off, the second to last layer of fibers 6 becomes the bottom layer of fibers 6, and the above method is repeated to peel them off.

[0029] While heating the resin matrix, the heating head 5 also provides a peeling force, so that the bottom layer of fibers 6 and the penultimate layer of fibers 6 are separated more quickly, thereby reducing the peeling resistance of the bottom layer of fibers 6, and the bottom layer of fibers 6 can be peeled off more quickly, thereby improving the peeling efficiency. In order to facilitate the control of the peeling force at the end of the heating head 5, a pressure sensor 17 is also provided at the end of the heating head 5. The heating temperature and the peeling force can be adjusted according to the detection results of the pressure sensor 17 and the temperature sensor 16, thereby controlling the peeling speed of the fibers 6. In order to reduce the resistance of the heating head 5 entering the resin matrix, the end of the heating head 5 is set to be conical, and its thickness gradually increases from the front end to the rear end.

[0030] In summary, the present invention realizes the recycling of part of the resin matrix, improves the recycling benefits of waste continuous fiber reinforced thermoplastic 3D printing composite materials, improves the recycling efficiency, and reduces the recycling cost.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials, characterized in that: The composite material (1) to be recycled is fixed on the bottom of a horizontal support plate (2), and a material receiving trough (3) is provided below the composite material (1); The heating head (5) is moved to contact the lower surface of the composite material (1), and the mechanical arm (4) is used to drive the heating head (5) to move in the opposite direction of the 3D printing of the composite material (1). The heating head (5) melts the resin matrix, and the fibers (6) in the melted area of ​​the resin matrix are peeled off by a traction mechanism. The molten resin matrix falls downward into the receiving trough (3). When recycling, the heating head (5) is inserted between the bottom layer of fibers (6) and the second to last layer of fibers (6) of the composite material (1), and then moves in the opposite direction of the 3D printing of the composite material (1), so that the resin matrix outside the bottom layer of fibers (6) is melted and the bottom layer of fibers (6) is peeled off.

2. The method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials according to claim 1, characterized in that: The traction mechanism comprises a recovery roller (7), a forming die (8) and a guide roller (19), and the fiber (6) passes through the guide roller (19) and the forming die (8) in sequence and is then wound around the recovery roller (7).

3. The method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials according to claim 1, characterized in that: The composite material (1) to be recycled is fixed to the lower surface of the horizontal support plate (2) by a clamping mechanism, wherein the clamping mechanism comprises a vertical first clamping plate (9), a vertical second clamping plate (10), a first fixing frame (11) and a second fixing frame (12), wherein the first clamping plate (9) and the second clamping plate (10) are parallel to each other, a clamping cavity is formed between the first clamping plate (9) and the second clamping plate (10), the upper ends of the first clamping plate (9) and the second clamping plate (10) are slidably connected to the horizontal support plate (2), the first fixing frame (11) is provided with a first push rod (13) threadedly connected to the first fixing frame (11), the second fixing frame (12) is provided with a second push rod (14) threadedly connected to the second fixing frame (12), the end of the first push rod (13) contacts the first clamping plate (9), and the end of the second push rod (14) contacts the second clamping plate (10); When fixing the composite material (1), the composite material (1) is placed in the clamping cavity, and the first push rod (13) and the second push rod (14) are rotated to push the first clamping plate (9) and the second clamping plate (10) toward the composite material (1) until the first clamping plate (9) and the second clamping plate (10) press the two side surfaces of the composite material (1).

4. The method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials according to claim 3, characterized in that: Anti-slip bosses are provided on the clamping surfaces of the first clamping plate (9) and the second clamping plate (10).

5. The method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials according to claim 1, characterized in that: A tungsten slurry heater (15) is arranged inside the heating head (5).

6. The method for recycling continuous fiber reinforced thermoplastic 3D printing composite materials according to claim 5, characterized in that: The heating head (5) is provided with a temperature sensor (16) and a pressure sensor (17).

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