CN114013069B

CN114013069B - Automatic laying and fused deposition compounding process of fiber reinforced thermoplastic material

Info

Publication number: CN114013069B
Application number: CN202111233343.9A
Authority: CN
Inventors: 黄志高; 蒋威; 周华民; 周何乐子; 杨飞; 杨爽; 刘文台
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2021-10-22
Filing date: 2021-10-22
Publication date: 2022-12-02
Anticipated expiration: 2041-10-22
Also published as: CN114013069A

Abstract

The invention relates to an automatic laying and fused deposition compounding process for a fiber reinforced thermoplastic material, and belongs to the field of molding and processing of fiber reinforced thermoplastic composite materials. Firstly, carrying out automatic fiber laying path planning on a main bearing structure of a target part to obtain a laying path, laying a continuous unidirectional fiber reinforced thermoplastic material prepreg tape, and carrying out in-situ curing molding on the tape by using a laser-assisted heating and cold pressing roller to obtain the main bearing structure of the target part which is automatically laid and molded; and then, slicing the functional assembly structure of the target part to obtain a fused deposition path, heating the laid main bearing structure to increase the surface temperature, performing wire feeding printing by using the segmented fiber reinforced thermoplastic material preimpregnated protofilaments according to the fused deposition path, and performing deposition molding on the functional assembly structure. The invention avoids the problems of continuous fiber fracture and interlayer damage caused by bolt connection drilling in the integral forming process, and can obviously improve the integral mechanical property of the component.

Description

Automatic laying and fused deposition compounding process of fiber reinforced thermoplastic material

Technical Field

The invention belongs to the field of molding and processing of fiber-reinforced thermoplastic composite materials, and particularly relates to an automatic laying and fused deposition compounding process of a fiber-reinforced thermoplastic material, in particular to a high-strength complex structural part molding method based on a fiber automatic laying and fused deposition compounding manufacturing process.

Background

The fiber reinforced resin matrix composite material is an ideal new generation structural material in the national strategic fields of aerospace, deep sea ships, automobiles and the like and the strut industry due to the advantages of high specific strength, designable performance, good fatigue resistance, good corrosion resistance and the like, particularly a continuous fiber reinforced thermoplastic composite material which has higher toughness and impact strength than a thermosetting composite material, can be repaired and easily recycled, and becomes a new leading edge of international competition in the field of composite materials.

At present, the main forming processes of carbon fiber thermoplastic composite materials include laying, winding and the like, wherein continuous carbon fiber prepregs (cloth/tape/wire) are laid on a substrate or wound on a core mould, and then are melted and cured through an oven, a mould pressing, an autoclave and the like. The single fiber laying forming is mainly used for large wall plate simple flat plate type components such as airplanes, ship body decks and the like, but the existing fused deposition technology for preparing thermoplastic composite material parts with complex shapes is still not mature enough, and the mechanical property, particularly the interlaminar shear strength is poor. The characteristics of the single process greatly limit the application range of the single process in the important fields of aerospace and the like.

With the continuous improvement of equipment lightweight and performance requirements, key parts in the field are gradually integrated and complicated, and composite material components are often added with reinforcing structures (reinforcing ribs/corner braces and the like), functional structures (turned edges/bosses/deep holes and the like) and assembling structures (clamping grooves/buckles and the like) on the basis of thin walls, and the complex structures are difficult to manufacture through the existing forming process and bring new challenges to the forming of fiber reinforced thermoplastic composite materials: 1) At present, a method of split forming and then connecting and assembling is mostly adopted, so that the product performance is difficult to ensure: 2) The failure to connect results in product design modification, resulting in weight redundancy; 3) The product characteristics make it difficult to form or modify the design in a split manner, which results in the inability to manufacture. Therefore, how to solve the bottleneck problem that the existing forming method is difficult to manufacture the bearing part with complex structures such as reinforcement, function, assembly and the like is an urgent need for engineering application of the carbon fiber thermoplastic composite material.

Disclosure of Invention

In order to solve the problem that the thermoplastic composite material with high strength and complex appearance is difficult to form, the invention manufactures the high-strength main bearing structure part based on the continuous unidirectional fiber laying process, forms complex functional structures such as reinforcing ribs, ribs and the like based on the fused deposition process, and realizes the integrated manufacture of the composite process through in-situ consolidation.

According to the purpose of the invention, the invention provides a fiber automatic laying and fused deposition composite process, which comprises the following steps:

(1) Carrying out automatic fiber laying path planning on a main load-bearing structure of the target part to obtain a laying path; according to the laying path, a continuous unidirectional fiber reinforced thermoplastic material prepreg tape is applied, and the tape is laid and cured in situ through laser-assisted heating and cold pressing rollers, so that a main load-bearing structure of the target part which is automatically laid and formed is obtained;

(2) And (2) slicing the functional assembly structure of the target part to obtain a fused deposition path, heating the laid main bearing structure obtained in the step (1) to increase the surface temperature, performing wire feeding printing by using short fiber reinforced thermoplastic material pre-impregnated protofilaments with the length of less than or equal to 300 micrometers according to the fused deposition path, and performing deposition molding on the functional assembly structure.

Preferably, between the step (1) and the step (2), a warm-pressing secondary forming step is further included, namely the laid main load-bearing structure is heated and embedded into a mold, and the mold-closing pressure is applied to warm-pressing secondary forming of the main load-bearing structure, so that the special-shaped structure of the main load-bearing structure is obtained.

Preferably, the special-shaped structure of the main force bearing structure is a boss and/or a curled edge.

Preferably, the temperature of said heating is below the melting point temperature of the thermoplastic material in the continuous unidirectional fibre reinforced thermoplastic prepreg tape and above the glass transition temperature.

Preferably, the continuous unidirectional fibre reinforced thermoplastic prepreg tape has a width of 6.35mm or 12.7mm and the chopped fibre reinforced thermoplastic prepreg filaments have a diameter of 1.75mm.

Preferably, the functional assembly structure is at least one of a stiffener, a snap, a gusset, and a rib.

Preferably, in the step (1), the laying speed is not lower than 50mm/s, and the pretightening force is 10N-50N; in the step (2), the wire feeding printing speed is not less than 15mm/s.

Preferably, the temperature of the heating in step (2) is 30 to 80 ℃ lower than the melting temperature of the thermoplastic material in the short fiber reinforced thermoplastic material prepreg strands.

Preferably, the thermoplastic material in the continuous unidirectional fibre reinforced thermoplastic prepreg tape is the same thermoplastic material as the thermoplastic material in the chopped fibre reinforced thermoplastic prepreg filaments.

Preferably, the continuous unidirectional fiber reinforced thermoplastic prepreg tape and the short fiber reinforced thermoplastic prepreg precursor are each independently selected from carbon fiber reinforced polyetheretherketone, carbon fiber reinforced polyetherketoneketone, glass fiber reinforced polypropylene or glass fiber reinforced polyphenylene sulfide.

Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

(1) The invention can realize the high-strength high-precision integral manufacture of the complex thermoplastic structural member. Compared with the split manufacturing and re-welding multi-step process tried in the prior art, the invention has the following obvious advantages: (1) the laser automatic laying forming continuous fiber reinforced composite material skeleton structure, the prepreg melting and solidifying synchronously when laying through rapid heating, realizes the high-efficiency manufacture of the non-autoclave, the continuous fiber can ensure the strength and rigidity of the main bearing part of the part; (2) the free forming of the composite and accessory structures can be realized by the fused deposition on the surface of the framework, and the framework is tightly bonded, so that the bottleneck problem that the complex component cannot be integrally formed is solved; (3) the laying die is manufactured by adopting fused deposition, so that the cost and time required by the manufacturing of the traditional die can be greatly saved, the molding efficiency of the complex component made of the thermoplastic composite material is obviously improved, and the low-cost manufacturing is realized.

(2) The invention provides an integrated composite process based on automatic fiber laying and fused deposition in the field of fiber reinforced thermoplastic composite material processing. Firstly, continuous carbon fiber prepreg is laid on a curved substrate according to a certain track, and is in-situ melted and solidified under the action of external heat sources such as laser and the like and a compression roller, so that a main bearing structure of continuous fiber laying is formed. And then performing fused deposition on the laying structure to obtain functional assembling structures such as reinforcing ribs, buckles and rib plates. The typical component with both mechanical property and complex appearance is obtained through composite process integrated molding.

(3) The invention integrates the advantages of AFP process and FDM process, ensures the main bearing part to utilize the strength and rigidity of the continuous fiber to the maximum extent by laying the fiber, and can realize flexible molding of complex structure by melting and depositing the filament; meanwhile, in-situ consolidation is realized through laser-assisted AFP and FDM processes without a subsequent melting and solidifying process; the integral forming avoids the problems of continuous fiber fracture and interlayer damage caused by bolt connection drilling, and can obviously improve the integral mechanical property of the member. The composite process can effectively solve the bottleneck problem that the existing forming method in the FRTP field is difficult to manufacture complex structures with enhanced, functional, assembled and the like.

(4) The tensile strength of the force-bearing part formed by automatically laying the fibers is not lower than 600MPa, and the interface strength of the part of the finally formed fibers, namely the automatically laid AFP and fused deposition FDM, is higher than 60MPa.

Drawings

FIG. 1 is a schematic of an automated fiber placement-fused deposition process route according to the present invention.

Fig. 2 is a schematic structural diagram of a complex force-bearing part forming device based on a fused deposition technology according to an embodiment of the application.

FIG. 3 is a schematic diagram of a complex typical structure component prepared by the composite process of the present invention; wherein, (a) is the sandwich structure of the wall panel, and (b) is the accessory structure of the side panel of the car seat.

FIG. 4 is a schematic structural diagram of a fiber placement system of an embodiment of the present application.

Fig. 5 is a schematic structural diagram of a fused deposition system according to an embodiment of the present application.

Fig. 6 is a structural schematic diagram of a force bearing part formed according to the embodiment of the application.

FIG. 7 is a technical route diagram of an automatic fiber placement-fused deposition integrated molding process according to the present invention.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:

100-fiber placement system:

110-a feed tray; 111-prepreg tape; 120-a compression roller; 130-a laser heating unit; 140-a front feed wheel; 150-a measuring wheel; 160-rear feeding wheel; 170-pneumatic scissors;

200-fused deposition System:

210-a forming table; 211-an electrical heating unit; 220-a print head; 230-an infrared preheating unit; 231-infrared heating lamps; 232-a reflector;

310-a cylinder screw; 320-step screw rod; 321-fulcrum.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The carbon fiber reinforced resin matrix composite material has the advantages of light weight, high specific strength, high specific stiffness, corrosion resistance and the like, becomes a key material for weight reduction and efficiency improvement of high-end equipment, and is widely applied to the national strategic fields of deep-sea ships, aerospace, automobiles and the like and the strut industry. Compared with thermosetting, the toughness and the impact strength of engineering thermoplastic (polyether-ether-ketone, polyphenylene sulfide and the like) composite materials are improved by more than 1 time, and the engineering thermoplastic (polyether-ether-ketone, polyphenylene sulfide and the like) composite materials can be repaired and easily recycled, so that the engineering thermoplastic (polyether-ether-ketone, polyphenylene sulfide and the like) composite materials become a new leading edge of international competition in the field of composite materials. Taking a carbon fiber reinforced polyether ether ketone (CF/PEEK) material as an example, the method described by the invention is adopted to obtain the carbon fiber reinforced polyether ether ketone complex force-bearing structural member.

FIG. 1 is a schematic of an automated fiber placement-fused deposition process route according to the present invention. The invention provides a complex thermoplastic part compounding process suitable for functional structures including reinforcing ribs, deep holes, buckles, angle braces and the like, which comprises the following steps of:

1) Preparing materials: the printing precursor comprises a rolled continuous unidirectional fiber reinforced thermoplastic material unidirectional prepreg narrow band with the width of 6.35mm and a short fiber reinforced thermoplastic material 3D printing precursor with the diameter of 1.75mm.

2) Planning a laying path: and (4) carrying out automatic fiber laying path planning on the main load-bearing structure, and determining a proper laying path. The track path obtained by combining software with topology optimization cannot generate the defects of overlapping and gaps.

3) Automatic Fiber Placement (AFP) molding: and (4) carrying out AFP process forming according to the planned path by adopting proper process parameters.

4) Warm pressing secondary forming: and (3) locally preheating the laying structure and embedding the laying structure into a die cavity of the main bearing structure for positioning, and carrying out warm-pressing secondary forming on the laying structure by virtue of the mold-closing pressure to obtain structures such as a boss and a turned edge.

5) Fused deposition path planning: and planning a deposition path of the functional structure to obtain a fused deposition path file.

6) Preheating a main bearing structure: the surface temperature of the laid main bearing structure is improved by adopting an infrared lamp tube preheating mode.

7) Fused Deposition (FDM) molding; and (4) converting the laying head into a fused deposition head to perform deposition molding on the complex functional structure.

8) And (3) post-treatment: after the formed parts are cooled, surface chemical treatment, mechanical treatment and the like are carried out to improve the surface precision and reduce the roughness.

In some examples, step 1) uses a uniform-grade carbon fiber reinforced thermoplastic prepreg tape having a width of 6.35mm and short carbon fiber reinforced thermoplastic prepreg filaments having a diameter of 1.75mm.

In some embodiments, in step 2), the track path obtained by combining software and topology optimization does not generate defects of overlapping and gaps.

In some embodiments, in the step 3), the fibers are automatically laid by laser-assisted heating, the laying speed is not lower than 50mm/s, the pretightening force is 10N, and the tensile strength of the formed bearing part is not lower than 600MPa.

In some embodiments, in the step 4), the laid, molded and cured main load-bearing structure is subjected to secondary warm pressing at 320 ℃ to form the required boss and curled edge structure, and the dimensional accuracy is 0.1mm.

In some embodiments, in the step 5), path planning software is adopted to perform molding path planning processing on complex functional parts such as reinforcing ribs, rib plates and the like, and a path planning file is output.

In some embodiments, in step 6), infrared lamp tube heating is adopted to make the surface temperature of the main force-bearing part after solidification and cooling reach the range of 30-80 ℃ lower than the melting temperature of the thermoplastic material, so as to perform subsequent melting deposition in an open environment on the surface.

In some embodiments, in step 7), the fiber placement head is converted into a fused deposition head for wire-feed printing, and the printing speed is not less than 15mm/s; the deposition head and the infrared lamp tube are kept in a relative static state in the moving process, the surface temperature of a deposition area is ensured to meet the requirement, and the interface strength of the automatic AFP (alpha-fetoprotein) laying of the final forming fiber and the fused deposition FDM part is higher than 60MPa.

In some embodiments, in step 8), the surface roughness is controlled to be less than 10um by mechanical surface treatment such as sand blasting, shot blasting and the like.

Fig. 2 is a technical route diagram of the automatic laying-fused deposition integrated forming process for the force-bearing component fiber with a complex shape. As shown in fig. 2 (a), firstly, unidirectional fiber reinforced thermoplastic prepregs are laid and molded on a pre-planned path by a fiber laying head, and are cumulatively molded layer by layer to the size thickness of the main load-bearing structure. Then as shown in (b) of fig. 2, transferring the laid and molded main bearing flat plate into a cavity of a hot-pressing mold, heating the mold to a temperature between the high elastic state and the molten state of the thermoplastic resin, and performing secondary warm-pressing to mold special structures such as a boss, a curled edge and the like of the bearing part. And (c) performing deposition molding on the printing wire material of the short fibers and the thermoplastic resin on the main bearing structure through a fused deposition head on a pre-planned path to prepare the functional assembling structures such as reinforcing ribs, buckles and the like, as shown in fig. 2. Finally, the force bearing part with a complex assembly structure is formed by an integrated process and equipment, and is shown as (d) in fig. 2.

Example 1

1) Preparing materials: unidirectional CF/PEEK prepreg tapes 6.35mm wide and chopped fiber reinforced polyetheretherketone (SCF/PEEK) prepreg strands 1.75mm in diameter.

2) Planning a laying path of the lower flat plate: and (3) performing path planning of automatic fiber laying on a lower flat plate of the honeycomb sandwich structure, and determining a proper laying path.

3) Automatic Fiber Placement (AFP) molding: and carrying out AFP process forming according to a planned path under the process conditions that the laser heating temperature is 380 ℃, the compression roller pressure is 0.7MPa, the laying speed is 50mm/s and the pre-tightening force is 10N.

4) Fused deposition slicing treatment: and slicing the middle-layer honeycomb structure to obtain a fused deposition path, and obtaining a fused deposition path file.

5) Preheating a main bearing structure: and (3) the surface temperature of the laid lower flat plate structure is increased to 280 ℃ by adopting an infrared lamp tube preheating mode.

6) Fused Deposition (FDM) molding; and (3) converting the laying head into a fused deposition head to carry out deposition molding of a honeycomb structure, wherein the temperature of a melting cavity is 350 ℃, the infrared preheating temperature is 280 ℃, and the deposition speed is 15mm/s.

7) Planning an upper flat plate laying path: and (4) performing path planning of automatic fiber laying on an upper flat plate of the honeycomb sandwich structure, and determining a proper laying path.

8) Automatic Fiber Placement (AFP) molding: and carrying out AFP process forming according to a planned path under the process conditions that the laser heating temperature is 380 ℃, the compression roller pressure is 0.7MPa, the laying speed is 50mm/s and the pre-tightening force is 10N.

9) And (3) post-treatment: the surface roughness of the steel plate is controlled to be below 10um by mechanical surface treatment such as sand blasting, shot blasting and the like.

Testing the interface in-situ bonding strength of the formed composite structure in the composite process, wherein the interface shear strength reaches 66% of the matrix strength and exceeds 70MPa; the tensile strength of the honeycomb flat plate reaches 650MPa; the surface roughness of the whole structure reaches Ra6.3, the precision of the flat plate is less than 100um, and the precision of the honeycomb structure is less than 10um. FIG. 3 is a schematic diagram of a complex typical structure component prepared by the composite process of the present invention; wherein (a) in fig. 3 is the core clamping structure of the wall panel of the present embodiment.

Example 2

1) Preparing materials: unidirectional CF/PEEK prepreg tapes of 6.35mm width and short fiber reinforced polyetheretherketone (SCF/PEEK) prepreg strands of 1.75mm diameter.

2) Planning a laying path: and (3) carrying out automatic fiber laying path planning on the main bearing flat plate of the automobile box type part structure, and determining a proper laying path.

4) And (3) locally preheating the laying structure and embedding the laying structure into a mold cavity of a mold of the main bearing structure for positioning, and carrying out warm-pressing secondary forming by means of mold closing pressure to obtain structures such as a boss.

5) Fused deposition slicing treatment: and slicing the three reinforcing ribs on the main bearing structure to obtain a fused deposition path, and obtaining a fused deposition path file.

6) Preheating a main bearing structure: the surface temperature of the laid bearing bottom plate structure is increased to 250 ℃ by adopting an infrared lamp tube preheating mode.

7) Fused Deposition (FDM) molding; and (3) converting the laying head into a fused deposition head for carrying out deposition molding on the reinforcing rib, wherein the temperature of a melting cavity is 350 ℃, the infrared preheating temperature is 280 ℃, and the deposition speed is 15mm/s.

8) And (3) post-treatment: the surface roughness of the steel plate is controlled to be below 10um by mechanical surface treatment such as sand blasting, shot blasting and the like.

Testing the interface in-situ bonding strength of the formed composite structure in the composite process, wherein the interface shear strength reaches 66% of the matrix strength and exceeds 70MPa; the tensile strength of a flat plate at the bottom of the automobile box-shaped part reaches 650MPa; the integral structure surface roughness reaches Ra6.3, and dull and stereotyped precision is less than 100um, and the honeycomb precision is less than 10um. FIG. 3 is a schematic diagram of a complex typical structure part prepared by the composite process of the present invention; wherein (b) in fig. 3 is a side plate attachment structure of a vehicle seat.

The process method can be realized by using the devices in fig. 4, fig. 5, fig. 6 and fig. 7, and fig. 4 is a schematic structural diagram of a complex force-bearing part forming device based on a fused deposition technology. The complex force-bearing part forming device based on the fused deposition technology comprises a fiber placement system 100 and a fused deposition system 200.

FIG. 5 is a schematic structural view of a fiber placement system. The fiber placement system 100 comprises a feeding tray 110, a press roller 120 and a laser heating unit 130, wherein the feeding tray 110 is used for installing the prepreg tape 111, the press roller 120 is used for feeding the prepreg tape 111 to a forming table 210 of the fused deposition system 200 after being subjected to pressure forming, and a light spot of the laser heating unit 130 irradiates the contact part of the lower part of the press roller and the forming table 210, and is used for heating the prepreg tape 111 so as to facilitate the press forming of the press roller 120.

The material of the prepreg tape in this example is a fiber reinforced thermoplastic composite. The width of the feed tray 110 corresponds to the width of the prepreg tape 111. Laser heating unit 130 is preferably a diode laser that can provide a 15mm x 45mm rectangular spot with a maximum power of 3KW, the spot size and power of which can be adjusted according to the material and requirements of the prepreg tape. The press roller 120 is made of a rigid material, has a Z-direction degree of freedom of 10mm stroke, and can be controlled to apply pressure by using an air cylinder or a hydraulic cylinder.

The fiber placement system 100 also includes a front feed wheel 140, a metering wheel 150, a rear feed wheel 160, and pneumatic shears 170. The front feeding wheel 140 is positioned between the feeding tray 110 and the measuring wheel 150, and is used for actively feeding the prepreg tape 111, the measuring wheel 150 is arranged between the front feeding wheel 140 and the rear feeding wheel 160, and the measuring wheel 150 is provided with an encoder for counting the feeding length in real time. The rear feeding wheel 160 is located between the measuring wheel 150 and the pneumatic scissors 170 for re-feeding the prepreg tape 111. The front feeding wheel 140 is closely adjacent to the feeding tray 110, the pressing roller 120 is arranged behind the rear feeding wheel 160, and the pneumatic scissors 170 are arranged between the rear feeding wheel 160 and the pressing roller 120 and used for cutting and feeding the prepreg tape 111.

The front feeding wheel 140, the rear feeding wheel 160 and the press roll 120 are controlled by an air cylinder or a hydraulic cylinder, wherein the front feeding wheel 140 and the rear feeding wheel 160 each comprise two matched rotating wheels, a gap is formed between the two rotating wheels, and the width of the gap is equal to the thickness of the prepreg tape 111.

FIG. 6 is a schematic diagram of a fused deposition system. The fused deposition system 200 comprises a printing head 220, a forming table 210 and an infrared preheating unit 230 arranged above the printing head, wherein the forming table 210 is provided with an electric heating unit 211 used for heating the forming table 210, and the electric heating unit 211 and the infrared preheating unit 230 provide a specific working environment for the printing head 220.

Different from the existing fused deposition system, the fused deposition system 200 in the present application does not include a sealed chamber for sealing the forming region, and is an open type, and the infrared preheating unit 230 is disposed above the print head 220, and the electric heating unit 211 is disposed below the forming table 210, so as to provide a working environment with a specific temperature for the print head 220, wherein the temperature of the forming region in the present embodiment is controlled to be 200-300 ℃. A high-temperature melting cavity is arranged above the printing head 220 of the fused deposition system 200, the printing material b is melted through the high-temperature melting cavity, the heating temperature is 200-400 ℃, the aperture of the nozzle is 1.75mm, and the nozzle is positioned below the high-temperature melting cavity.

The infrared preheating unit 230 includes an infrared heating lamp 231 and a reflecting shade 232 disposed on an upper portion of the infrared heating lamp, and the reflecting shade is used for reflecting light emitted by the infrared heating lamp to a printing area to heat the printing area.

The infrared heating lamp is long tubular, the opening of reflector is square, the direction of arranging the infrared heating lamp is parallel to the direction of the prepreg tape fed by the fiber placement system, and the infrared heating lamp irradiates and extends to the position of the press roller, for example, the heating area a of the infrared heating lamp is 15mm multiplied by 30mm.

Furthermore, the infrared heating lamp is connected with the outer edge of the reflecting cover through a screw rod to realize linkage, and the height and the position of the reflecting cover are adjusted through the screw rod so as to adjust the relative distance between the infrared heating lamp and the reflecting cover to realize the control of a heating area; or the reflector is in a fold umbrella shape, and the opening degree of the reflector is adjusted by adjusting the fold degree of the fold umbrella shape so as to control the size of the heating area.

Further, the infrared preheating unit 230 further includes an infrared temperature probe and a control system, the control system is connected to the infrared temperature probe and the infrared heating lamp, the infrared temperature probe is used for detecting the temperature of the printing region, and the control system is used for controlling the power of the infrared heating lamp according to the temperature detected by the infrared temperature probe so that the temperature of the printing region is within a preset range. For example, a 15mm wide infrared lamp may be used to preheat the substrate in the range of 0-10mm before and after the printhead at 80W to 250 deg.C, and an infrared temperature probe may be used to measure temperature in real time and perform pid feedback thermostatic control

The device also comprises a working mode switching and interference preventing system, wherein the working mode switching and interference preventing system comprises an air cylinder screw 310 and a stepping screw 320, and the working mode switching and interference preventing system comprises an air cylinder screw and a stepping screw, wherein the air cylinder screw is arranged on the compression roller and used for controlling the stroke of the compression roller; one end of the stepping screw is connected with the fused deposition system, the other end of the stepping screw is connected with the air cylinder screw, the middle of the stepping screw is movably connected with a fulcrum 321, when the air cylinder screw moves upwards, the stepping screw moves downwards around the fulcrum, and when the air cylinder screw moves downwards, the stepping screw moves upwards around the fulcrum. Two independent screw mechanisms are additionally arranged on a printing head and a compression roller of the fused deposition system to provide a larger up-down stroke so as to avoid the problem of mutual interference. The high-efficiency and rapid laying forming of the bearing structure is carried out through the fiber laying system, the air cylinder screw 310 moves to enable the working mechanism of the fiber laying system to ascend and enter a stop working state, the forming shape of the working mechanism can be controlled through the pressure of the stroke control press roller of the air cylinder screw 310, the stepping screw 320 descends to enable the fused deposition system to descend and enter a working state, functional structures such as a corner brace c, a high rib e and a buckle d are formed through fused deposition on a laid flat plate, and the structural schematic diagram of the formed bearing part is shown in fig. 7.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. The automatic fiber placement and fused deposition composite process is characterized by comprising the following steps of:

(1) Carrying out automatic fiber laying path planning on a main force-bearing structure of the target part to obtain a laying path; according to the laying path, a continuous unidirectional fiber reinforced thermoplastic material prepreg tape is applied, and the tape is laid and cured in situ through laser auxiliary heating and cold pressing rollers, so that a main bearing structure of the target part which is automatically laid and formed is obtained;

(2) Slicing the functional assembly structure of the target part to obtain a fused deposition path, heating the paved main bearing structure obtained in the step (1) to increase the surface temperature, performing wire feeding printing by using short fiber reinforced thermoplastic material pre-impregnated protofilaments with the length of less than or equal to 300 micrometers according to the fused deposition path, and performing deposition molding on the functional assembly structure; the heating temperature is 30-80 ℃ lower than the melting temperature of the thermoplastic material in the short fiber reinforced thermoplastic material pre-impregnated protofilament; the thermoplastic material in the continuous unidirectional fiber reinforced thermoplastic material prepreg tape and the thermoplastic material in the short fiber reinforced thermoplastic material prepreg protofilament are the same thermoplastic material;

and (3) between the step (1) and the step (2), a warm-pressing secondary forming step is further included, namely the paved main bearing structure is heated and embedded into a mold, and the mold-closing pressure is applied to warm-pressing secondary forming of the main bearing structure, so that the special-shaped structure of the main bearing structure is obtained.

2. The automated fiber placement and fused deposition composite process according to claim 1, wherein the profile structure of the primary load-bearing structure is a boss and/or a crimp.

3. The automated fiber placement and fused deposition composite process according to claim 1, wherein the warm press overmolding heating is at a temperature below the melting point temperature of the thermoplastic material in the continuous unidirectional fiber reinforced thermoplastic prepreg tape and above the glass transition temperature.

4. The automated fiber placement and fused deposition compounding process of claim 1, wherein the continuous unidirectional fiber reinforced thermoplastic prepreg tape has a width of 6.35mm or 12.7mm and the chopped fiber reinforced thermoplastic prepreg filaments have a diameter of 1.75mm.

5. The automated fiber placement and fused deposition composite process according to claim 1, wherein the functional mounting structure is at least one of a stiffener, a snap, a gusset, and a rib.

6. The automated fiber placement and fused deposition composite process according to claim 1, wherein in step (1), the placement speed is not lower than 50mm/s, and the pre-load force is 10N to 50N; in the step (2), the wire feeding printing speed is not less than 15mm/s.

7. The automated fiber placement and fused deposition composite process according to claim 1, wherein the continuous unidirectional fiber-reinforced thermoplastic prepreg tape and the short fiber-reinforced thermoplastic prepreg precursor are each carbon fiber-reinforced polyetheretherketone, carbon fiber-reinforced polyetherketoneketone, glass fiber-reinforced polypropylene or glass fiber-reinforced polyphenylene sulfide.