Preparation process and device of orientation-variable continuous fiber reinforced thermoplastic bar

Abstract

The invention relates to the technical field of fiber reinforced thermoplastic composite material manufacturing, and discloses a preparation process and device of a variable orientation continuous fiber reinforced thermoplastic bar. The preparation process comprises the following steps: arranging a continuous fiber reinforced thermoplastic unidirectional prepreg tape on a tension bracket of a preheating system at a certain orientation angle, and preheating; enabling the preheated one-way prepreg tape to form a bundled bar blank with a specified orientation angle through guiding and drafting, feeding the bundled bar blank into a heater for bundling and heating, and performing extrusion molding through a mouth mold of a heating mold under drafting to obtain a bar-shaped profile; and cooling and shaping to obtain the variable orientation continuous fiber reinforced thermoplastic bar. The one-way prepreg tape is subjected to secondary impregnation by melting thermoplastic resin in the pultrusion process, meanwhile, multiple strands of prepreg tapes are curled and arranged through a preheating system in the multi-stage pultrusion process and are led out at a certain twisting angle, specified angle orientation of overall fibers of the bar is achieved, and the anti-shearing capacity of the bar is improved.

Description

Technical Field

[0001] This application relates to the technical field of manufacturing fiber-reinforced thermoplastic composites, and particularly to a preparation process and device for variable-orientation continuous fiber-reinforced thermoplastic rods. Background Art

[0002] Continuous fiber-reinforced thermoplastic composites exhibit significant advantages in the high-end manufacturing field due to their unique combination of properties, such as extremely strong environmental adaptability, lightweight and high-strength characteristics, and good biocompatibility. In the preparation process of continuous fiber-reinforced thermoplastic composites, pultrusion is a widely used material forming method. Its process can achieve continuous automated production with high production efficiency and can prepare profiles with consistent cross-sections but various shapes. However, there are still certain problems in the existing preparation processes, such as uneven fiber impregnation and low shear resistance caused by uniaxial fiber arrangement, with only 150 - 230 MPa.

[0003] The patent with the publication number ZL88100835 proposed a method for continuous fiber-reinforced thermoplastic polymer profiles, which improves the impregnation effect by pressing the roving impregnated with thermoplastic resin to form a preform. The specific scheme is to first impregnate the fiber with molten thermoplastic resin, and then press it when passing through a rectangular flat-head heating die to compact the roving to form a preform, and force the molten thermoplastic resin into the fiber for impregnation. Due to the relatively high viscosity of the resin used to prepare the thermoplastic resin fiber, this method has high operation difficulty in industrial production, poor production continuity, and low finished product strength.

[0004] CN1730270A introduced a pultrusion method and a forming die for thermoplastic composites. By mixing two types of fibers in a certain weight ratio, preheating through a preforming die, changing the fiber ratio, melting and fully impregnating the two in the forming die, and finally extruding and cooling and shaping through a die to obtain the finished product. This method improves the fiber impregnation problem. However, the reinforcing fibers are arranged along the axis, with a single fiber orientation direction, and the properties of the prepared products are low, unable to meet the requirements of complex stress structures.

[0005] Based on this, how to develop a high-strength continuous fiber-reinforced thermoplastic pultruded product is an urgent problem to be solved in the thermoplastic pultrusion process. Summary of the Invention

[0006] This application provides a preparation process and device for variable-orientation continuous fiber-reinforced thermoplastic rods, aiming to solve the technical problems of uneven fiber impregnation and low shear resistance of products caused by uniaxial fiber arrangement existing in the existing thermoplastic pultrusion process.

[0007] To achieve the above objectives, this application adopts the following technical solutions.

[0008] In the first aspect of the present application, a preparation process for a variable-orientation continuous fiber-reinforced thermoplastic rod is provided, which is characterized by comprising:

[0009] S1, arranging the continuous fiber-reinforced thermoplastic unidirectional prepreg on the tension rack of the preheating system at a certain orientation angle for preheating;

[0010] S2, forming a bundled rod blank with a specified orientation angle from the preheated continuous fiber-reinforced thermoplastic unidirectional prepreg through guiding and drawing, feeding it into a heater for bundling and heating, and extruding and forming it through the die of a heating mold under drawing to obtain a rod-shaped profile;

[0011] S3, cooling and shaping the rod-shaped profile to obtain a variable-orientation continuous fiber-reinforced thermoplastic rod.

[0012] Preferably, the continuous fiber-reinforced thermoplastic unidirectional prepreg comprises a thermoplastic resin matrix and continuous fibers uniformly dispersed in the thermoplastic resin matrix;

[0013] In the continuous fiber-reinforced thermoplastic unidirectional prepreg, the mass fraction of the thermoplastic resin is 30 - 60%, and the volume fraction of the continuous fibers is 30 - 70%.

[0014] Preferably, the thermoplastic resin matrix comprises at least one of polyethylene, polypropylene, polyphenylene sulfide, thermoplastic polyimide, polyether ether ketone, polyarylether ketone, polyetherimide resin or ABS resin;

[0015] The continuous fibers include any one of carbon fibers, glass fibers, quartz fibers, natural fibers or aramid fibers.

[0016] Preferably, the preheating system comprises a tension rack and a sleeve with an opening on one side, and the tension rack is fixedly arranged inside the sleeve;

[0017] The tension rack is a cylinder with two bottom surfaces of different sizes, and its side surface has a plurality of inclined grooves; both ends of each inclined groove are respectively connected to the two bottom surfaces of the tension rack, and the width of the inclined groove gradually becomes smaller; the wider end of the inclined groove serves as a feeding guide;

[0018] Blind holes are uniformly arranged on the larger bottom surface of the tension rack, and heating rods and thermocouples are arranged in the blind holes for heating the tension rack;

[0019] The bottom surface of the sleeve is provided with a hole adapted to the smaller bottom surface of the tension rack, and through holes are arranged on the outer side of the bottom surface, and heating rods and thermocouples are arranged in the through holes for heating the sleeve.

[0020] Preferably, the width of the continuous fiber-reinforced thermoplastic unidirectional prepreg is 5 - 50 mm; and its thickness is 0.1 - 1 mm.

[0021] Preferably, after the unidirectional prepreg tape is bundled at a specified orientation angle and heated and formed, the angle between the continuous fibers and the axis of the rod-shaped profile is 20° to 70°.

[0022] Preferably, the diameter of the die is 1 to 20 mm.

[0023] Preferably, the drawing speed is 5 to 500 mm / min.

[0024] Preferably, the temperature of the preheating is the glass transition temperature Tg of the corresponding thermoplastic resin + (5 to 100) °C;

[0025] In step S2, the heating is gradient heating from low to high, and the heating temperature is 100 to 500 °C;

[0026] In step S3, the cooling rate of the cooling and shaping is 10 to 100 °C / min.

[0027] In the second aspect of the present application, there is provided a device for preparing a variable-orientation continuous fiber-reinforced thermoplastic rod, including a preheating system, a guide, a heater, a cooling device, and a tractor;

[0028] The preheating system includes a tension frame and a sleeve with an opening on one side, and the tension frame is fixedly arranged inside the sleeve;

[0029] The tension frame is a cylinder with two bottom surfaces of different sizes, and its side surface has a plurality of inclined grooves; both ends of each inclined groove are respectively connected to the two bottom surfaces of the tension frame, the width of the inclined groove gradually becomes smaller, and the wider end of the inclined groove serves as the feeding guide;

[0030] Blind holes are uniformly arranged on the larger bottom surface of the tension frame, and heating rods and thermocouples are arranged in the blind holes for heating the tension frame;

[0031] The bottom surface of the sleeve is provided with a hole adapted to the smaller bottom surface of the tension frame, and through holes are arranged on the outer side of the bottom surface, and heating rods and thermocouples are arranged in the through holes for heating the sleeve;

[0032] A die is arranged at the outlet end of the heater;

[0033] The continuous fiber-reinforced thermoplastic unidirectional prepreg tape enters the preheating system from the guiding hole of the preheating system, is preheated, and then enters the heater through the guide under the traction of the tractor for bundling and heating, and then is extruded through the die of the heater and enters the cooling device, and the variable-orientation continuous fiber-reinforced thermoplastic rod is obtained after cooling.

[0034] Compared with the prior art, the beneficial effects of the present application are:

[0035] This application uses well-impregnated unidirectional prepreg tapes as raw materials, and in pultrusion molding, the materials are secondarily impregnated by heating and melting thermoplastic resins, greatly improving the problem of difficult impregnation in thermoplastic pultrusion processes. At the same time, in the multi-stage pultrusion molding process of this application, through the preheating system, multiple strands of unidirectional prepreg tapes are curled and arranged and led out at a certain orientation angle, realizing the twisting of the overall fibers of the rod, greatly improving the shear resistance of the rod; in addition, by changing the fiber orientation, the pultruded profiles also exhibit good mechanical properties in non-axial directions, expanding the application fields of thermoplastic pultruded rods.

[0036] The preparation process of this application not only has excellent product performance, but also is simple and convenient, with a high degree of continuity, greatly improving the preparation efficiency, solving the industrialization problem of pultrusion molding of high-performance thermoplastic composites, and enabling rapid batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 is the preparation device for variable-orientation continuous fiber-reinforced thermoplastic rods of this application;

[0039] Figure 2 is the right view of the preheating system;

[0040] Figure 3 is the left view of the preheating system;

[0041] Figure 4 is the front view of the tensioning frame;

[0042] Figure 5 is the left view of the tensioning frame;

[0043] Figure 6 is the schematic diagram and morphology diagram of the glass fiber-reinforced polyaryletherketone twisted rod prepared by this application;

[0044] Figure 7 is the physical diagram of the glass fiber-reinforced polyaryletherketone twisted rod with different fiber orientation angles prepared by this application;

[0045] Figure 8 is the physical diagram of the glass fiber-reinforced polyaryletherketone twisted rod, carbon fiber-reinforced polyaryletherketone, and quartz fiber-reinforced polyaryletherketone twisted rod prepared by this application;

[0046] The reference numerals are: 1, preheating system; 2, guide; 3, heater; 4, cooling device; 5, tractor; 11, tension frame; 12, sleeve; 111, inclined groove; 112, feed guiding hole; 113, larger bottom surface of the tension frame; 114, smaller bottom surface of the tension frame; 115, heating rod; 116, thermocouple; 121, bottom surface of the sleeve. Detailed implementation manners

[0047] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0048] In the following description of this embodiment, the terms "include", "comprise", "have" and "contain" are all open-ended terms, that is, they are meant to include but not limited to.

[0049] In the following description of this embodiment, the term "and / or" is used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, B exists alone, and both A and B exist simultaneously. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects.

[0050] In the following description of this embodiment, the term "at least one" means one or more, and "a plurality" means two or more. "At least one of the following items" or its similar expressions refer to any combination of these items, including any combination of single item or plural items. For example, "at least one of a, b or c", or, "at least one of a, b and c" can both represent: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0051] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0052] Those skilled in the art should understand that in the following description of the embodiments of the present application, the sequence numbers do not mean the order of execution, and some or all of the steps can be executed in parallel or successively. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0053] Those skilled in the art should understand that the numerical ranges in the embodiments of this application should be understood as specifically disclosing each intermediate value between the upper and lower limits of the range. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0054] Unless otherwise specified, the technical / scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application pertains. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0055] In a first aspect, this application provides a preparation process for a variable - orientation continuous - fiber - reinforced thermoplastic rod, including:

[0056] S1, arranging the continuous - fiber - reinforced thermoplastic unidirectional prepreg on the tension rack of the pre - heating system at a certain orientation angle and performing pre - heating;

[0057] The continuous - fiber - reinforced thermoplastic unidirectional prepreg includes a thermoplastic resin matrix and continuous fibers uniformly dispersed in the thermoplastic resin matrix; wherein the mass fraction of the thermoplastic resin is 30 - 60%, and the volume fraction of the continuous fibers is 30 - 70%. Among them, the thermoplastic resin matrix includes at least one of polyethylene, polypropylene, polyphenylene sulfide, thermoplastic polyimide, polyether ether ketone, polyarylether ketone, polyetherimide resin or ABS resin; the continuous fibers include any one of carbon fibers, glass fibers, quartz fibers, natural fibers or aramid fibers.

[0058] In this application, the pre - heating system includes a tension rack and a sleeve with an opening on one side, and the tension rack is fixedly arranged inside the sleeve;

[0059] The tension rack is a column with two bottom surfaces of different sizes, and its side surface has a plurality of inclined grooves; both ends of each inclined groove are respectively connected to the two bottom surfaces of the tension rack, the width of the inclined groove gradually becomes smaller, and the wider end of the inclined groove serves as the feeding guiding hole; blind holes are uniformly arranged on the larger bottom surface of the tension rack, and heating rods and thermocouples are arranged in the blind holes for heating the tension rack;

[0060] The bottom surface of the sleeve is provided with a hole adapted to the smaller bottom surface of the tension rack, and through holes are arranged on the outer side of the bottom surface, and heating rods and thermocouples are arranged in the through holes for heating the sleeve.

[0061] In this application, the unidirectional prepreg is placed in the inclined groove of the tension rack and arranged on the tension rack to obtain a specific orientation angle; by changing the direction of the inclined groove, the orientation angle of the unidirectional prepreg is adjusted. This application can customize the tension rack with different inclined groove directions. According to actual needs, by replacing the tension rack with inclined grooves of different directions, different fiber orientation angles can be obtained.

[0062] In this application, the width of the continuous fiber reinforced thermoplastic unidirectional prepreg needs to be within a specific range to achieve the expected effect. If it is too wide, it is not conducive to twisting during preheating; if it is too narrow, it is not conducive to molding. Its width is preferably 5 - 50 mm, more preferably 5 - 10 mm; its thickness is preferably 0.1 - 1 mm, more preferably 0.1 - 0.5 mm.

[0063] In this application, the preheating temperature is higher than the glass transition temperature Tg of the corresponding thermoplastic resin, preferably 5 - 100 °C higher than the glass transition temperature of the corresponding thermoplastic resin. By preheating, the continuous fiber reinforced thermoplastic unidirectional prepreg is maintained at a certain temperature to avoid uneven heating during subsequent heating.

[0064] S2, through guiding and drawing, the preheated continuous fiber reinforced thermoplastic unidirectional prepreg is formed into a bundled bar blank with a specified orientation angle, sent into a heater for bundling and heating, and extruded and formed through the die of a heating die under drawing to obtain a rod-shaped profile; wherein, the speed of the drawing is preferably 5 - 500 mm / min.

[0065] In this application, the heating of the pultrusion die adopts multi-stage heating, and its temperature increases from low to high, and the heating temperature is 100 - 500 °C. Specifically, different temperatures are set in multiple heating modules in the heater to heat the bundled bar blank with a specified orientation angle. Taking the processing temperature of polyaryletherketone resin as an example, the temperature gradient in the heater is preferably 310 °C, 340 °C, 375 °C, and 395 °C. Through multi-stage heating, the thermoplastic resin is fully melted and the secondary impregnation is completed; at the same time, the excess resin is extruded during this process and finally formed to obtain a rod-shaped profile. Among them, the diameter of the die is 1 - 20 mm, preferably 3 - 10 mm.

[0066] In this application, heating can adopt infrared heating, electric heating, heat-conducting oil, steam heating, microwave heating, or electromagnetic induction heating.

[0067] In this application, for the rod-shaped profile after bundling and heating, the orientation angle range of the continuous fiber and the axis of the bar is 20° - 70°

[0068] S3. Cool and shape the rod-shaped profile to obtain a variable-orientation continuous fiber-reinforced thermoplastic rod.

[0069] In this application, the cooling rate of the cooling and shaping is 10 - 100 °C / min. The cooling method can adopt air cooling, water cooling or natural cooling.

[0070] This application uses a well-impregnated unidirectional prepreg as the raw material, and in the pultrusion process, the material is secondarily impregnated by heating and melting the thermoplastic resin, greatly improving the problem of difficult impregnation in the thermoplastic pultrusion process. At the same time, in the multi-stage pultrusion process of this application, through the preheating system, multiple strands of unidirectional prepregs are oriented, curled and arranged at a specified angle and led out at a certain orientation angle, realizing the twisting of the overall fibers of the rod, greatly improving the shear resistance of the rod; in addition, by changing the fiber orientation, the pultruded profile also shows good mechanical properties in the non-axial direction, expanding the application field of the thermoplastic pultruded rod.

[0071] The preparation process of this application not only has excellent product performance, but also is simple and convenient, with a high degree of continuity, greatly improving the preparation efficiency, solving the industrialization problem of the pultrusion of high-performance thermoplastic composites, and being able to produce quickly and in batches.

[0072] In the second aspect, this application provides a preparation device for a variable-orientation continuous fiber-reinforced thermoplastic rod, as Figure 1 shown, which includes a preheating system 1, a guide 2, a heater 3, a cooling device 4 and a tractor 5;

[0073] Figure 2 and Figure 3 are respectively the right view and the left view of the preheating system. The preheating system includes a tension frame 11 and a sleeve 12 with an opening on one side. The tension frame is fixedly arranged inside the sleeve.

[0074] Figure 4 and Figure 5 are respectively the front view and the left view of the tension frame 11. The tension frame 11 is a cylinder with two bottoms of different sizes, and its side has a plurality of inclined grooves 111; both ends of each inclined groove are respectively connected to the two bottoms of the tension frame, the width of the inclined groove gradually becomes smaller, and the wider end of the inclined groove is used as the feed guiding hole 112. Blind holes are uniformly arranged on the larger bottom surface 113 of the tension frame, and heating rods 115 and thermocouples 116 are arranged in the blind holes for heating the tension frame.

[0075] The bottom surface 121 of the sleeve 12 is provided with a hole adapted to the smaller bottom surface 114 of the tension frame, and a circle of through holes is arranged on the outer side of the bottom surface. Heating rods 115 and thermocouples 116 are arranged in the through holes for heating the sleeve; in this application, the sleeve can adopt an integral sleeve or a detachable sleeve.

[0076] The outlet end of the heater is provided with a die.

[0077] The continuous fiber reinforced thermoplastic unidirectional prepreg tape enters the preheating system through the feed guiding hole of the preheating system, is preheated, bundled and heated in the heater under the traction of the tractor through the guide, and then enters the cooling device after being extruded through the die of the heater. After cooling, the variable orientation continuous fiber reinforced thermoplastic rod is obtained.

[0078] The following further illustrates the present application through examples.

[0079] Example 1

[0080] This example provides a preparation process for pultrusion molding of glass fiber reinforced polyaryletherketone (GF / PAEK) composite rods. The unidirectional prepreg tape used is a narrow tape of continuous glass fiber reinforced polyaryletherketone unidirectional prepreg, with a width of 10 mm and a thickness of 0.2 mm. It is purchased from Heilongjiang Yingchuang New Materials Co., Ltd., and the brand is SCF11-1000.

[0081] Place multiple strands of narrow tapes of glass fiber reinforced polyaryletherketone unidirectional prepreg on the tension rack of the preheating system 1, fix the narrow tapes and achieve a fixed angle orientation, and preheat at 200 °C.

[0082] Transport the bundled rod blank with the specified orientation angle obtained after preheating to the heater 3 through the guide 2, and heat it by infrared heating. The heating process adopts multi-stage heating, and different temperatures are set in multiple heating modules in the heater. The temperature gradients are 310 °C, 340 °C, 375 °C and 395 °C to ensure that the polyaryletherketone resin is fully melted, complete the secondary impregnation, and then extrude the excess resin through the die of the heater for preliminary forming. Control the die size to be 3.3 mm.

[0083] After heating and melting and resin extrusion, the rod is preliminarily formed, enters the cooling device 4 for rapid cooling to obtain the finished rod, and air cooling is used. The cooling speed is 50 °C / min; then through the cutting machine 6, the glass fiber reinforced polyaryletherketone (GF / PAEK) composite rod is obtained, that is, the glass fiber reinforced polyaryletherketone (GF / PAEK) twisted rod. During the pultrusion process, the drawing speed of the whole process is controlled by the drawing machine 5, and the drawing speed is set to 450 mm / min.

[0084] During the preparation process, according to the method of Example 1, by changing the fiber content, drawing speed, twisting angle and die diameter in the narrow tape of glass fiber reinforced polyaryletherketone unidirectional prepreg, the glass fiber reinforced polyaryletherketone (GF / PAEK) composite rods of Examples 2-10 are respectively prepared, that is, the glass fiber reinforced polyaryletherketone (GF / PAEK) twisted rods.

[0085] Comparative Example 1

[0086] Comparative Example 1 provides a preparation process for unidirectional GF / PAEK rods. The unidirectional prepreg used in Comparative Example 1 is from the same batch as that in Example 1. Its width is 100 mm and its thickness is 0.2 mm. It is purchased from Heilongjiang Yingchuang New Materials Co., Ltd., and its grade is SCF11-1000. The preparation method includes:

[0087] Cut the SCF11-1000 unidirectional prepreg into blanks of appropriate size, and initially weld the blanks by an ultrasonic spot welder to fix them into a thermoplastic composite semi-finished product. Then, hot press the semi-finished product in a precision flat vulcanizer to obtain a 6-mm laminated plate. Cut the finished laminated plate into rectangular cross-section rods with a size of 6 mm * 6 mm by a water cutting knife, and prepare unidirectional GF / PAEK unidirectional rods after grinding and polishing.

[0088] The specific preparation process parameters and double shear strength test results of the glass fiber reinforced polyaryletherketone (GF / PAEK) twisted rods prepared in Examples 1-10 and the GF / PAEK unidirectional rods in Comparative Example 1 are shown in Table 1.

[0089] To verify the morphological characteristics of the twisted rods prepared in the examples, the made rods were observed for their metallographic morphology. Figure 6 In Figure a, it is a schematic diagram of the twisted rod, in Figure b, it is the cross-sectional morphology of the rod, and in Figure c, it is the longitudinal-sectional morphology of the rod. It can be seen from Figure 6 that there are no obvious defects and pores in the entire cross-section of the twisted rod. And with the twisting of the rod, the twisting angle at the edge of the rod in the longitudinal section is larger, while the part close to the center of the rod has a smaller twisting angle.

[0090] Table 1 Process parameters and double shear strength of continuous glass fiber reinforced polyaryletherketone (GF / PAEK) rods

[0091]

[0092] It can be seen from Table 1 that the thermoplastic GF / PAEK twisted rods prepared in this application have excellent anti-shear ability, up to more than 300 MPa at most, which are all higher than the unidirectional GF / PAEK unidirectional rods in Comparative Example 1. It is applicable to high-end application fields with high shear strength requirements, such as the aviation and aerospace fields.

[0093] It can be seen from the comparison between Example 1 and Example 2 that the increase in the fiber orientation angle is beneficial to the improvement of the double shear strength of the twisted bar. This is because when the pultruded twisted bar bears the radial shear load, since the force direction is not directly perpendicular to the actual fiber orientation direction, the twisted bar can disperse a part of the shear force along the actual fiber orientation direction of the twisted fiber, and the fiber is subjected to a tensile force under this part of the force; actually, the shear force along the radial direction of the twisted fiber is reduced, resulting in the twisted bar being able to withstand a higher shear load. The physical diagrams of the twisted bars with different fiber orientation angles are as Figure 7 shown. As the twisting angle increases, the double shear strength of the bar increases.

[0094] It can be seen from the comparison between Example 2, Example 3, Example 6 and Example 7 that the appropriate reduction of the drawing speed is beneficial to the improvement of the double shear strength of the twisted bar. This is because when the bundled bar embryo passes through the heating section of pultrusion, the resin in the narrow band is heated and melted and then extruded. The reduction of the drawing speed is beneficial to the extrusion of the resin, increasing the fiber content of the bar, and the double shear strength of the bar is improved.

[0095] It can be seen from the comparison between Example 3, Example 5 and Example 6 that the diameter of the bar does not affect the double shear strength of the bar. Among the bars with different diameters prepared by different processes, when the twisting angle and fiber content are kept consistent, the double shear strengths of the bars are not much different.

[0096] It can be seen from the comparison between Example 8, Example 9 and Example 10 that the fiber content in the glass fiber reinforced polyaryletherketone narrow band significantly affects the double shear strength of the twisted bar. This is because the fiber content in the narrow band directly affects the fiber content in the finished twisted bar, and the increase in the fiber content leads to the improvement of the double shear strength of the twisted bar.

[0097] Referring to Example 10, continuous fiber reinforced polyaryletherketone twisted bars of Examples 11-13 were prepared using different fibers, and their process parameters and double shear strength test results are shown in Table 2. Among them, the physical diagrams of the glass fiber reinforced polyaryletherketone twisted bar, carbon fiber reinforced polyaryletherketone, and quartz fiber reinforced polyaryletherketone twisted bar are as Figure 8 shown.

[0098] Table 2 Process parameters and double shear strength of different fiber reinforced polyaryletherketone twisted bars

[0099]

[0100] It can be seen from Table 2 that the polyaryletherketone twisted bars prepared using different reinforcing fibers all have good shear strength.

[0101] Although the present application has been described in detail in this specification with general descriptions and specific embodiments, modifications or improvements can be made to it based on the present application, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present application fall within the scope of protection claimed by the present application.

Claims

1. A preparation process for a variable-orientation continuous fiber-reinforced thermoplastic rod, characterized in that, Including: S1, arranging the continuous fiber reinforced thermoplastic unidirectional prepreg tape on the tension rack of the preheating system at a certain orientation angle for preheating; S2, forming a bundled bar blank with a specified orientation angle from the preheated continuous fiber reinforced thermoplastic unidirectional prepreg tape through guiding and stretching, feeding it into a heater for bundling and heating, and extruding and forming it through the die of a heating die under stretching to obtain a rod-shaped profile; S3, cooling and shaping the rod-shaped profile to obtain a variable orientation continuous fiber reinforced thermoplastic rod.

2. The preparation process according to claim 1, characterized in that, The continuous fiber reinforced thermoplastic unidirectional prepreg tape includes a thermoplastic resin matrix and continuous fibers uniformly dispersed in the thermoplastic resin matrix; In the continuous fiber reinforced thermoplastic unidirectional prepreg tape, the mass fraction of the thermoplastic resin is 30-60%, and the volume fraction of the continuous fibers is 30-70%.

3. The preparation process according to claim 2, characterized in that, The thermoplastic resin matrix includes at least one of polyethylene, polypropylene, polyphenylene sulfide, thermoplastic polyimide, polyether ether ketone, polyarylether ketone, polyetherimide resin, or ABS resin; The continuous fibers include any one of carbon fibers, glass fibers, quartz fibers, natural fibers, or aramid fibers.

4. The preparation process according to claim 1, characterized in that, The preheating system includes a tension rack and a sleeve with an opening on one side, and the tension rack is fixedly arranged inside the sleeve; The tension rack is a column with two bottom surfaces of different sizes, and its side has a plurality of inclined grooves; both ends of each inclined groove are respectively connected to the two bottom surfaces of the tension rack, and the width of the inclined groove gradually becomes smaller; the wider end of the inclined groove serves as a feeding guide; Blind holes are uniformly arranged on the larger bottom surface of the tension rack, and heating rods and thermocouples are arranged in the blind holes for heating the tension rack; The bottom surface of the sleeve is provided with a hole adapted to the smaller bottom surface of the tension rack, and through holes are arranged on the outer side of the bottom surface. Heating rods and thermocouples are arranged in the through holes for heating the sleeve.

5. The preparation process according to claim 1, characterized in that, The width of the continuous fiber reinforced thermoplastic unidirectional prepreg tape is 5-50 mm; its thickness is 0.1-1 mm.

6. The preparation process according to claim 1, characterized in that, After the unidirectional prepreg tape is bundled, heated, and formed at a specified orientation angle, the angle between the continuous fibers and the axis of the rod-shaped profile is 20°-70°.

7. The preparation process according to claim 1, characterized in that, The diameter of the die is 1-20 mm.

8. The preparation process according to claim 1, characterized in that, The stretching speed is 5-500 mm / min.

9. The preparation process according to claim 1, characterized in that, In step S1, the temperature of the preheating is the glass transition temperature Tg of the corresponding thermoplastic resin + (5-100) °C; In step S2, the heating is gradient heating from low to high, and the heating temperature is 100-500 °C; In step S3, the cooling rate of the cooling and shaping is 10-100 °C / min.

10. An apparatus for preparing a continuously reinforced thermoplastic rod with variable orientation, characterized in that, Including a preheating system, a guide, a heater, a cooling device, and a tractor; The preheating system includes a tension rack and a sleeve with an opening on one side, and the tension rack is fixedly arranged inside the sleeve; The tension rack is a column with two bottom surfaces of different sizes, and its side has a plurality of inclined grooves; both ends of each inclined groove are respectively connected to the two bottom surfaces of the tension rack, the width of the inclined groove gradually becomes smaller, and the wider end of the inclined groove serves as a feeding guide; Blind holes are evenly arranged on the relatively large bottom surface of the tension frame, and heating rods and thermocouples are arranged in the blind holes for heating the tension frame; The bottom surface of the sleeve is provided with holes adapted to the relatively small bottom surface of the tension frame, and through holes are provided on the outer side of the bottom surface. Heating rods and thermocouples are arranged in the through holes for heating the sleeve; A die is arranged at the outlet end of the heater; The continuous fiber reinforced thermoplastic unidirectional prepreg enters the preheating system from the guiding holes of the preheating system, is preheated, and then enters the heater through the guide under the traction of the tractor for bunching and heating. After being extruded through the die of the heater, it enters the cooling device, and the variable orientation continuous fiber reinforced thermoplastic rod is obtained after cooling.

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