CN116278105A - Fiber wire preparation method and equipment for friction stir welding and welding method - Google Patents

Abstract

The invention discloses a fiber filament material preparation method and equipment for friction stir welding and a welding method. The preparation method includes the following steps: S1. The bundled fiber material is stretched and pre-impregnated with a sizing glue to form a unidirectional thin-layer fiber belt. The thermoplastic polymer is melted and plasticized and coated on the unidirectional thin-layer fiber tape to form a fiber-coated tape; S2, the fiber-coated tape is wound axially to form a unidirectional multi-layer fiber/polymer preform with a circular cross section. Impregnated wire material; S3, cutting the unidirectional multi-layer fiber/polymer prepreg wire material and keeping it in a semi-continuous state, heat-melting treatment and cooling to obtain a fiber wire material that is fused after cutting, when the fiber wire material of the present invention is welded It can be evenly and omnidirectionally distributed in the welding part, thereby significantly improving the strength of the weld seam. The slit fibers can be distributed in a 360-degree direction under the drive of the high-speed rotating stirring head, and the fibers can be obtained from all angles of the weld seam. Reinforcement avoids the possible anisotropy of the mechanical properties of the weld due to fiber reinforcement.

Description

Fibrous filament preparation method and equipment for friction stir welding and welding method

technical field

The invention relates to the field of welding technology, in particular to a fiber wire material preparation method and equipment for friction stir welding and a welding method.

Background technique

Material welding can significantly improve the continuity of product production. For more complex metal products, a reasonable welding process can significantly shorten the manufacturing cycle, reduce product weight, and improve the flexibility of product shape and structural design. Therefore, welding has become It has attracted wide attention as an important product forming process and is widely used. Among them, friction stir welding (FSW), as a solid-state welding process, relies on the friction between the rotating tool and the workpiece material to generate heat, which in turn causes the area near the friction stir welding tool to soften, mix and finally achieve the bonding of the workpiece. Workpieces often have better mechanical properties after friction stir welding. At present, this process is mainly used for the connection of light alloy and low carbon steel, etc., and is also used for the welding of polymers in a small amount.

Compared with other welding methods, polymer friction stir welding has the advantages of low temperature, severe plastic deformation, and high joint quality, but it also has many limitations and deficiencies. For example, the welding quality is greatly affected by the process, so welding The process window is narrow, and the optimal welding process is not easy to be stable in practical applications. area.

Contents of the invention

Purpose of the invention: The purpose of the present invention is to provide a fiber filament preparation method and equipment for friction stir welding and a welding method, which can significantly improve the mechanical properties of the weldment.

Technical solution: In the first aspect, the fiber filament preparation method for friction stir welding provided by the present invention comprises the following steps:

Step S1, the bundled fiber material is stretched and pre-impregnated with a sizing glue to form a unidirectional thin-layer fiber tape, and the thermoplastic polymer is melted and plasticized and coated on the unidirectional thin-layer fiber tape to form a fiber-coated tape; Step S2 1. Winding the fiber-coated tape axially to form a circular unidirectional multilayer fiber/polymer prepreg filament; step S3, cutting the unidirectional multilayer fiber/polymer prepreg filament and maintaining half After the continuous state, heat-melt treatment and cooling to obtain fiber filaments that are cut and fused.

Further, in the step S1, the thermoplastic polymer is the same as the base material to be welded.

Further, in the step S1, the fiber content of the fiber-coated tape is 40%-60%.

Further, in the step S2, the cross-section delamination line of the unidirectional multilayer fiber/polymer prepreg is an Archimedes spiral.

Further, in the step S3, the cutting ratio accounts for 70-90% of the entire circular section, and the cutting length is 1.5-2.5 times the diameter of the friction stir welding head.

Further, in the step S3, the cut unidirectional multi-layer fiber/polymer prepreg filament is axially pressed and remelted during hot-melt treatment.

On the other hand, the fiber filament prepared by the above method is applied to a thermoplastic polymer friction stir welding welding process. Specifically, the welding method includes the following steps:

Step 1. After repairing and leveling the part to be welded of the parts to be connected, remove the material from the middle of the part to be welded;

Step 2, embedding or melting the prepared fiber filament into the part to be welded where the material has been removed, and flattening the part to be welded;

Step 3. Butt the parts to be welded of the two parts to be connected, apply a lateral force, and press and fix them. After the high-speed rotation of the stirring head, the two parts are connected.

Further, the material removed in the middle of the part to be welded in step 1 is consistent with the volume of the fiber filament material to be embedded or melted in step 2. During the welding process of step 3, the amount of pressing down is controlled to be the shoulder of the stirring head after the welding wire is pressed in. The end surface exceeds the upper surface of the welding wire by 0.05-0.15mm, and the amount of pressure is less than or equal to the difference between the thickness of the weldment and the length of the stirring needle.

In another aspect, the present invention provides a fiber filament preparation equipment for friction stir welding, comprising:

The extruder is used to extrude thermoplastic polymer after melting and plasticizing; the spreading roller is used to spread the bundled fiber material to form a unidirectional thin layer fiber dry tape; the fiber tape bonding roller is used to make the unidirectional The thin-layer fiber dry tape is pre-impregnated with sizing glue to form a whole piece of unidirectional thin-layer fiber tape; the dipping head is used to coat the melted and plasticized thermoplastic polymer on the unidirectional thin-layer fiber tape to form a fiber-coated tape; the shaft Direction winder, used to wind the fiber coating tape in the axial direction to form unidirectional multi-layer fiber/polymer prepreg; traction rollers, used to wind unidirectional multi-layer fiber/polymer prepreg Traction to crawler tractor; longitudinal cutter for longitudinal slitting of unidirectional multilayer fiber/polymer prepreg; hot melt oven for longitudinal slitting of unidirectional multilayer fiber/polymer prepreg The final fracture is remelted, and the fiber filament is obtained after remelting and cooling.

Further, it also includes a speed-regulating pair of rollers, the speed of which is the same as that of the traction pair of rollers, and is lower than the speed of the crawler tractor.

Beneficial effects: the invention can significantly improve the strength of the weld; the invention avoids the possible anisotropy of the mechanical properties of the weld due to fiber reinforcement; the invention can effectively avoid the weld that is easily produced by ordinary polymer friction stir welding The probability of the existence of pores or gaps; the invention is convenient to use, and the refusion after the wire material is cut can significantly improve the convenience of use, and the welding is easy to implement; the wire material preparation and welding process are green and pollution-free.

Description of drawings

Fig. 1 is the schematic diagram of the preparation equipment structure of fiber silk material of the present invention;

Fig. 2 is the physical figure of fusion after cutting the fiber filament material of the present invention;

Fig. 3 is the physical figure of welding of the present invention;

Fig. 4 is the SEM characterization figure of the fiber wire material of the embodiment 1 of the present invention at the workpiece weld;

Fig. 5 is the SEM characterization figure of the embodiment of the present invention 2 using polycarbonate as a raw material without fiber material after welding;

Fig. 6 is the sample outline drawing before and after the test of the welding test sample of embodiment 1 of the present invention and embodiment 2;

Fig. 7 is a SEM characterization diagram of the welding seam of the workpiece connected in Example 3 of the present invention.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1 is the equipment for preparing the used fiber silk material of friction stir welding of the present invention, and this Figure 1 also shows the preparation process of fiber silk material, and equipment mainly comprises extruder 1, creel 2 , Spreading roller 4, fiber tape bonding roller 5, dipping head 7, axial winder 8, traction roller 9, crawler tractor 10, longitudinal cutter 11, hot melt oven 12 and speed regulating roller 13.

The extruder 1 is connected with the impregnation head 7, and one side of the extruder 1 is provided with a creel 2, a yarn spreading roller 4, and a fiber tape bonding roller 5, and the other side of the extruder 1 is provided with an axial winder 8 in sequence , traction pair of rollers 9, hot-melt oven 12 and speed-regulating pair of rollers 13, in addition between traction pair of rollers 9 and hot-melt oven 12, crawler tractor 10 and longitudinal cutter 11 are arranged, and longitudinal cutter 11 is arranged on crawler traction Directly above machine 10.

The steps of preparing fiber filaments by the above-mentioned equipment are as follows:

In step (1), the thermoplastic polymer is melted and plasticized by the extruder 1 and then entered into the dipping head 7;

In step (2), the specific fiber material is placed in the creel 2. At this time, the fiber material is in the form of a bundle, and the fiber bundle 3 forms a unidirectional thin-layer fiber dry belt after being broadened by the spreading roller 4; the creel 2 The number can be one or more, and the number of spreading rollers 4 should be consistent with creel 2;

In step (3), several flattened fiber strips are pre-impregnated with a small amount of sizing glue to form a whole piece of unidirectional thin-layer fiber strips 6 when they pass through the fiber strip bonding roller 5, and the fiber strips 6 also enter the impregnation head 7 , the fiber belt 6 is evenly coated with polymer high-temperature melt to form a fiber-coated belt; controlling the coating amount of the fiber-coated belt can control the fiber content and ensure that the fibers are evenly distributed in the coated belt, the present embodiment , the fiber content is kept between 40% and 60%;

In step (4), the fiber-coated tape is wound axially by the subsequent axial winder 8 to form a circular unidirectional multilayer fiber/polymer prepreg filament;

Step (5), the wire enters the crawler tractor 10 under the action of the traction pair roller 9, and is cut by the longitudinal cutter 11 and kept in a semi-connected state;

Step (6), when the wire in the semi-continuous state passes through the hot-melt oven 12, a small amount of polymer at the fracture site melts, and at the same time, it is subjected to the slight retarding force of the speed-regulating pair of rollers 13 behind, so that the molten polymer is compressed And bonded to each other, thereby forming the fiber filaments 14 that are fused after cutting. The filaments are subsequently wound or coiled for later use. The speed of the speed-regulating pair of rollers 13 can be kept consistent with the speed of the traction pair of rollers 9. Their speed Both are 2 to 5% lower than the speed of crawler traction.

The fiber filament material prepared by the above method is applied to the welding process of thermoplastic polymer friction stir welding, specifically, including the following steps:

1) After repairing and leveling the part to be welded of the parts to be connected, remove an appropriate amount of material from the middle of the part to be welded;

2) After embedding or melting the prepared wire into the part to be welded, flatten the part to be welded;

3) Apply an appropriate amount of lateral force after docking the parts to be welded of the two parts to be connected, and then press and fix them on the workbench. Under the determined welding process conditions, after the high-speed rotation of the stirring head, the two parts are connected .

Wherein, the material removed in the middle of each part to be welded in step 1) is consistent with the volume of the wire to be embedded or melted in step 2).

The welding process conditions in step 3) mainly include the amount of pressing force and welding speed. Generally, the amount of pressing force is controlled so that the end surface of the shoulder of the stirring head exceeds the upper surface of the welding wire by 0.05-0.15mm after the welding wire is pressed in, and the amount of pressing force Less than or equal to the difference between weldment thickness and pin length.

Example 1

In order to demonstrate the implementation effect more easily, this example conducts friction stir welding for transparent polycarbonate weldments, and the main raw materials used include polycarbonate (PC, melting volume rate is 24cm ³ /10min, (300°C/1.2kg)) And carbon fiber (12K, T700), are commercially available.

The whole process mainly includes two steps of wire preparation and welding. The wire preparation process is as follows:

Firstly, the polycarbonate is melted and plasticized by the extruder 1 and then enters the impregnation head 7. At the same time, a bundle of carbon fibers is placed in the creel 2, and after being spread by the spreading roller 4, a unidirectional thin film is formed. A layer of fiber dry tape is pre-impregnated with a small amount of sizing glue to form a whole piece of unidirectional thin-layer fiber tape 6 when passing through the fiber tape bonding roller 5, and the fiber content is kept at 50%. The fiber tape 6 also enters the impregnation head 7 , the fiber belt 6 is evenly coated with polycarbonate high-temperature melt to form a fiber-coated belt;

Secondly, the fiber-coated tape is wound in the axial direction by the subsequent axial winder 8, and the cross-section gradually forms an Archimedes spiral, forming a circular unidirectional multi-layer fiber/polymer prepreg wire, The wire enters the crawler tractor 10 under the action of the traction roller 9, and is cut by the longitudinal cutter 11 and kept in a semi-continuous state; the cutting ratio accounts for 80% of the entire circular fiber/polymer prepreg cross section, Slitting length is 12mm (friction stir welding head diameter is 6mm), and the wire material of semi-continuous state is when passing through hot-melt oven 12, and the polymer at fracture part melts in a small amount; The speed of the rollers 9 is consistent, and their speeds are all 3% lower than the speed of the crawler traction. Therefore, the semi-continuous state of the wire will be slightly retarded by the speed-adjusting pair of rollers 13, and the molten polymer will be pressed and bonded to each other. , thereby forming a cut and re-fused fiber filament 14, which is subsequently wound or coiled for use. The shape of the cut and fused fiber filaments is shown in Figure 2. Fusion refers to that in the present invention, the polymer of the fiber filament at the fracture is melted, the molten polymers are pressed and bonded to each other, and the polymers at the fracture are connected in an adhesive manner after cooling, wherein, at the fracture, the adhesive Fibers that are cut after merging remain cut.

The prepared wire is then used for friction stir welding, mainly including:

1) Obtain the joints to be connected with polycarbonate as raw material by hot pressing or other processes, repair and flatten the parts to be welded, and remove the material equivalent to the cross section of the wire in the middle of the parts to be welded;

2) After embedding the prepared wire into the part to be welded, flatten the part to be welded again;

3) Apply an appropriate amount of lateral force after docking the parts to be welded of the two parts to be connected, and then press and fix them on the workbench. Under the determined welding process conditions, after the high-speed rotation of the stirring head, the two parts are connected as one.

The above process and the shape effect of the welded product are shown in Figure 3.

Among them, since the wire material is 0.2mm away from the outer upper wall of the weldment after it is embedded in the part to be welded, the downward pressure of the welding head is controlled to 0.30mm, the thickness of the weldment is 2mm, and the length of the selected stirring needle is 1.5mm .

SEM was used to characterize the welds of the connected workpieces, and the results are shown in Figure 4. In Figure 4, it can be seen that the fibers of almost the same length are evenly distributed in an arc shape, and the reinforcement of the fibers can be predicted from its structure. The slit fibers can be distributed in 360 degrees under the drive of the high-speed rotating stirring head. At this time, all angles of the weld can be reinforced by fibers, avoiding the mechanical properties of the weld that may be caused by fiber reinforcement. Anisotropy, the application of wire can also effectively avoid the probability of weld pores or gaps that are easily produced by ordinary polymer friction stir welding.

Cut out a rectangular test sample from the connected workpiece and perform a tensile mechanical performance test. The shape results are shown in Figure 6, where Figures 6a and 6b show the shape of the sample before and after the test, respectively. From Figure 6b, it can be seen that the tensile The fracture does not occur at the weld, but in the affected area a little closer to the weld, which is enough to indicate that the mechanical properties of the weld are better than the affected area of the base metal. The test results are listed in Table 1.

From the results in Table 1, it can be seen that the tensile strength of the weld seam obtained in this embodiment is close to that of the base metal. Therefore, the wire reinforced weldment of the present invention has a fiber distribution structure of a specific form, exhibits the characteristics of excellent mechanical properties, and has excellent application prospect.

Example 2

In order to compare with Example 1, similar to Example 1, this comparative example also uses commercially available polycarbonate (melting volume rate is 24cm ³ /10min) as the base material raw material, and the difference is that Example 2 does not use fiber filaments material, the welding process is mainly as follows: through hot pressing or other processes to obtain the joints to be connected with polycarbonate as raw material, and then apply an appropriate amount of lateral force after the parts to be welded of the two joints to be welded, and then compress Fixed on the workbench, under the determined welding process conditions, after the high-speed rotation of the stirring head, the two pieces are connected as one.

SEM is used to characterize the welding seam of the connected workpiece, and the result is shown in Figure 5. It can be seen from Figure 5 that there are many gaps and gaps at the joint of the weld seam, so the strength of the weld seam can be predicted to be low. great.

A rectangular test piece was cut out from the connected workpiece, and the tensile mechanical performance test was carried out. The shape results are also shown in Figure 6. Figures 6c and 6d show the shape of the sample before and after the test, respectively. From Figure 6d, it can be seen that the tension The tensile fracture appeared in the weld without suspense, which is enough to indicate that the mechanical properties of the weld need to be improved.

The results of the tensile mechanical properties test are also listed in Table 1. At this time, the tensile fractures all occurred at the welds, indicating that the mechanical properties of the welds are still low. As can be seen from the results in Table 1, the tensile strength of the weld seam obtained in this comparative example is very different from that of Example 1, indicating that the use of fiber filaments has a greater impact on the welding quality.

Example 3

In order to compare with Example 1, this comparative example also carries out friction stir welding for transparent polycarbonate weldments, and the main raw materials used include polycarbonate (melting volume rate is 24cm ³ /10min) and carbon fiber (12K, T700), both is commercially available.

The whole process mainly includes two steps of wire material preparation and welding. The wire material preparation process is similar to the existing conventional long fiber reinforced polymer pellets except that no cutting is performed: after the polycarbonate is melted and plasticized through the extruder Entering the dipping head, at the same time, the carbon fiber tow placed in the creel is also introduced into the dipping head, and the fibers are dipped in polycarbonate high-temperature melt in the dipping head to form fibers with irregular cross-sections / Polymer prepreg filaments that are subsequently drawn, wound or coiled for use as continuous filaments.

The prepared wire was then used for friction stir welding as follows:

1) Obtain the joints to be connected with polycarbonate as raw material by hot pressing or other processes, repair and flatten the parts to be welded, and remove the material equivalent to the cross section of the wire in the middle of the parts to be welded;

2) After embedding the prepared wire into the part to be welded, cut off as needed, and flatten the part to be welded again;

3) Apply an appropriate amount of lateral force after docking the parts to be welded of the two parts to be connected, and then press and fix them on the workbench. Under the determined welding process conditions, after the high-speed rotation of the stirring head, the two parts are connected as one.

SEM is used to characterize the welding seam of the connected workpiece, and the result is shown in Figure 7. It can be seen from Figure 7 that the fiber distribution at the welding seam is very chaotic, and the fiber length difference is also large. The distribution of fibers in each direction It's also confusing.

The rectangular test specimens were cut out from the connected workpieces, and the tensile mechanical properties were tested. The results are also listed in Table 1. At this time, the tensile fractures all occurred at the welds, indicating that the mechanical properties of the welds are still low. It can be seen from the results in Table 1 that the tensile strength of the weld seam obtained in this comparative example is far from that of the examples, indicating that the preparation method of the fiber filament has a great influence on the welding quality.

Example 4

In this example, friction stir welding is carried out for nylon weldments. The main raw materials used include nylon (PA66, melting volume rate: 23cm ³ /10min) and glass fiber (12K, T700), both of which are commercially available.

The whole process mainly includes two steps of wire preparation and welding. The wire preparation process is as follows:

First, the PA66 is melted and plasticized by the extruder 1 and then enters the impregnation head 7. At the same time, two bundles of carbon fibers are placed in the two creels 2 respectively, and are formed after being stretched by two spreading rollers 4. Unidirectional thin-layer fiber dry belt, two unidirectional thin-layer fiber dry belts are pre-impregnated with a small amount of sizing glue when they pass through the fiber belt bonding roller 5 to form a whole piece of unidirectional thin-layer fiber belt 6, and the fiber content is kept at 60%. The fiber strip 6 also enters the impregnation head 7, and the fiber strip 6 is evenly coated with PA66 high-temperature melt to form a fiber-coated strip;

Secondly, the fiber-coated tape is wound in the axial direction by the subsequent axial winder 8, and the cross-section gradually forms an Archimedes spiral, forming a circular unidirectional multi-layer fiber/polymer prepreg wire, The wire enters the crawler tractor 10 under the action of the traction roller 9, and is cut by the longitudinal cutter 11 and kept in a semi-continuous state; the cutting ratio accounts for 90% of the entire circular fiber/polymer prepreg cross section, Slitting length is 9cm (friction stir welding head diameter is 6mm), and the wire material of semi-continuous state is when passing through hot-melt oven 12, and the polymer at fracture place melts in a small amount, simultaneously, due to the speed of speed-regulating pair roller 13 and traction pair The speed of the rollers 9 is the same, and their speeds are all 5% lower than the speed of the crawler traction. Therefore, the semi-continuous state of the wire will be slightly retarded by the speed-adjusting pair of rollers 13, and the molten polymer will be pressed and bonded to each other. , thereby forming a cut and re-fused fiber filament 14, which is subsequently wound or coiled for use. The appearance of the fiber filaments fused after cutting is also similar to that in FIG. 2 .

The prepared wire was then used for friction stir welding as follows:

1) Obtain the joints to be connected with polycarbonate as raw material by hot pressing or other processes, repair and flatten the parts to be welded, and remove the material equivalent to the cross section of the wire in the middle of the parts to be welded;

2) After embedding the prepared wire into the part to be welded, flatten the part to be welded again;

3) Apply an appropriate amount of lateral force after docking the parts to be welded of the two parts to be connected, and then press and fix them on the workbench. Under the determined welding process conditions, after the high-speed rotation of the stirring head, the two parts are connected as one.

Among them, since the wire material is 0.2mm away from the outer upper wall of the weldment after it is embedded in the part to be welded, the downward pressure of the welding head is controlled to 0.35mm, the thickness of the weldment is 2mm, and the length of the selected stirring needle is 1.5mm .

The rectangular test specimens were cut out from the connected workpieces, and the tensile mechanical properties were tested. The test results are listed in Table 1. From the results in Table 1, it can be seen that the tensile strength of the weld seam obtained in this embodiment is close to that of the base metal. Therefore, the wire reinforced weldment of the present invention has a fiber distribution structure of a specific form, exhibits the characteristics of excellent mechanical properties, and has excellent application prospect.

Example 5

In order to compare with Example 4, this comparative example also carries out non-cut fiber filament friction stir welding for nylon weldments, and the main raw materials used include nylon (melting volume rate is 23cm ³ /10min) and carbon fiber (12K, T700) , are commercially available.

The whole process mainly includes two steps of wire material preparation and welding. The wire material preparation process is similar to the existing conventional long fiber reinforced polymer pellets except that no cutting is performed: the nylon is melted and plasticized by the extruder and then enters the In the impregnation head, at the same time, the carbon fiber tow placed in the creel is also introduced into the impregnation head, and the fiber is impregnated with nylon high-temperature melt in the impregnation head to form a fiber/polymer preform with irregular cross-section. Impregnated wire, which is subsequently pulled, wound or coiled for use as continuous wire.

The prepared wire was then used for friction stir welding as follows:

1) Obtain the connector to be connected with nylon as raw material by hot pressing or other processes, repair and flatten the part to be welded, and remove the material equivalent to the cross section of the wire in the middle of the part to be welded;

2) After embedding the prepared wire into the part to be welded, cut off as needed, and flatten the part to be welded again;

3) Apply an appropriate amount of lateral force after docking the parts to be welded of the two parts to be connected, and then press and fix them on the workbench. Under the determined welding process conditions, after the high-speed rotation of the stirring head, the two parts are connected as one.

The welded joints of the connected workpieces were characterized by SEM, and the results were similar to those in Example 3. The distribution of fibers at the welded joints was chaotic, the difference in fiber length was also large, and the distribution of fibers in various directions was also chaotic.

The rectangular test specimens were cut out from the connected workpieces, and the tensile mechanical properties were tested. The results are also listed in Table 1. At this time, the tensile fractures all occurred at the welds, indicating that the mechanical properties of the welds are still low. It can be seen from the results in Table 1 that the tensile strength of the weld seam obtained in this comparative example is far from that of the examples, indicating that the preparation method of the fiber filament has a great influence on the welding quality.

Example 6

The difference from Example 1 is that in this example, the fiber content of the fiber-coated tape is 40%; the cutting ratio accounts for 70% of the entire circular section, the cutting length is 15mm, and the pressing amount of the welding head is controlled to 0.25mm.

Example 7

The difference from Example 1 is that in this example, the fiber content of the fiber-coated tape is 60%; the cutting ratio accounts for 90% of the entire circular section, the cutting length is 15mm, and the pressing amount of the welding head is controlled to 0.32mm.

Table 1 Comparison of tensile properties of several weldments

Claims (10)

1. A fiber wire preparation method for friction stir welding, characterized in that, comprising the following steps: Step S1, the bundled fiber material is stretched and pre-impregnated with a sizing glue to form a unidirectional thin-layer fiber tape, and the thermoplastic polymer is melted and plasticized and coated on the unidirectional thin-layer fiber tape to form a fiber-coated tape; Step S2, axially winding the fiber-coated tape to form a circular unidirectional multilayer fiber/polymer prepreg filament; Step S3, cutting the unidirectional multi-layer fiber/polymer prepreg and keeping it in a semi-continuous state, then heat-melting and cooling to obtain cut and re-fused fiber filaments. 2. A method for preparing fiber filaments for friction stir welding according to claim 1, characterized in that: in the step S1, the thermoplastic polymer is the same as the base material to be welded. 3. A method for preparing fiber filaments for friction stir welding according to claim 1, characterized in that: in the step S1, the fiber content of the fiber coating tape is 40%-60%. 4. A method for preparing fiber filaments for friction stir welding according to claim 1, characterized in that: in the step S2, the cross-section layered line of the unidirectional multilayer fiber/polymer prepreg filament for the Archimedes spiral. 5. A method for preparing fiber filaments for friction stir welding according to claim 1, characterized in that: in the step S3, the cutting ratio accounts for 70% to 90% of the entire circular section, and the cutting length is 1.5 to 2.5 times the diameter of the friction stir welding head. 6. A kind of fiber filament material preparation method for friction stir welding according to claim 1, is characterized in that: in described step S3, the unidirectional multi-layer fiber/polymer prepreg filament material after cutting is in During the hot melt treatment, the axial force is extruded and remelted. 7. according to any one of claim 1-6 for the welding method of the fiber wire material prepared by the fiber wire material preparation method of friction stir welding, it is characterized in that, comprises the steps: Step 1. After repairing and leveling the part to be welded of the parts to be connected, remove the material from the middle of the part to be welded; Step 2, embedding or melting the prepared fiber filament into the part to be welded where the material has been removed, and flattening the part to be welded; Step 3. Butt the parts to be welded of the two parts to be connected, apply a lateral force, and press and fix them. After the high-speed rotation of the stirring head, the two parts are connected. 8. The welding method for fiber filaments for friction stir welding according to claim 7, characterized in that the volume of the material removed from the middle of the part to be welded in step 1 and the volume of the fiber filaments to be embedded or melted in step 2 Keep consistent, during the welding process of step 3, the amount of pressing down is controlled so that the end surface of the shoulder of the stirring head exceeds the upper surface of the welding wire by 0.05-0.15mm after the welding wire is pressed in, and the amount of pressing down is less than or equal to the distance between the thickness of the weldment and the length of the stirring pin. difference. 9. A fiber filament material preparation equipment for friction stir welding, characterized in that, comprising: An extruder (1), used for extruding the thermoplastic polymer after melting and plasticizing; Spreading roller (4), used for forming a unidirectional thin-layer fiber dry belt after spreading the bundled fiber material; The fiber tape bonding roller (5) is used for forming the unidirectional thin-layer fiber dry tape pre-preg sizing glue into a whole piece of unidirectional thin-layer fiber tape (6); A dipping head (7), used for coating the unidirectional thin-layer fiber tape (6) with the melted and plasticized thermoplastic polymer to form a fiber-coated tape; An axial winder (8), used to wind the fiber-coated tape axially to form a unidirectional multilayer fiber/polymer prepreg; Pulling pair of rollers (9), used for pulling the unidirectional multi-layer fiber/polymer prepreg wire to the crawler tractor (10); A longitudinal cutter (11) is used for longitudinally cutting the unidirectional multilayer fiber/polymer prepreg filament; The hot-melt oven (12) is used for remelting the fracture of the unidirectional multi-layer fiber/polymer prepreg longitudinally cut, and cooling after remelting to obtain the fiber filament. 10. A kind of fiber silk material preparation equipment for friction stir welding according to claim 9, is characterized in that: also comprise speed-regulating pair of rollers (13), its speed is identical with the speed of traction pair of rollers (9), And less than the speed of crawler tractor (10).

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