Method and device for ultrasonic additive manufacturing of thermoplastic composite materials

Abstract

The present invention relates to a method and device for ultrasonic additive manufacturing of thermoplastic composite materials. The method comprises: applying a certain pressure, and applying ultrasonic vibration as an energy input, to act jointly at an interface between two layers of thermoplastic composite materials of a workpiece; converting mechanical energy into internal energy to heat the interface between the thermoplastic composite materials in an extremely short period of time; tightly bonding the two layers of composite materials by means of an additive manufacturing method that carries out melting under the action of thermo-mechanical coupling to form a strong bond by means of molecular diffusion; and repeating the process above, such that each layer of composite material is bonded to the previous layer by means of ultrasonic vibration, thereby realizing layer-by-layer additive manufacturing of thermoplastic composite materials of the workpiece. On this basis, the preparation of parts having complex contour profiles by ultrasonic additive manufacturing is realized by means of various contours of molds. The present invention realizes additive manufacturing of complex contour profiles by controlling the translation of an ultrasonic additive manufacturing tool head and the rotation of materials. The present invention has the characteristics of good continuity, high additive manufacturing speed, high additive manufacturing energy and uniform energy.

Description

Method and device for ultrasonic additive thermoplastic composite material TECHNICAL FIELD

[0001] The present application relates to a method and device for ultrasonic additive thermoplastic composite material. The method and device are applied to additive manufacturing of thermoplastic composite material parts with complex profile, and have the characteristics of simple operation, high additive efficiency and no damage to raw materials. Since the ultrasonic action time experienced by each position on the additive path is short, heat is generated instantaneously, and the thermal deformation of the material is less. At the same time, the ultrasonic additive tool head moves continuously and rotates at high speed, which can improve the ultrasonic additive energy and realize continuous and uniform additive process, thereby reducing defects and pores, and preparing high-strength thermoplastic composite material parts. BACKGROUND

[0002] Thermoplastic composite materials have the advantages of low weight, low cost, short heat forming manufacturing cycle of parts, good impact resistance, good toughness, room temperature storage, and re-molding, and are widely used in aerospace, automotive, military and other fields.

[0003] Common thermoplastic composite forming processes include hot press forming, injection molding, pultrusion forming, winding forming, laying forming, 3D printing forming, etc. Among them, hot press forming has high forming efficiency and can well control the influence of parameters on forming quality, but the equipment cost is high, and it is difficult to form parts with complex profile; injection molding can form parts with complex structure, but it is mainly used for processing and forming of long fiber thermoplastic composite materials or short fiber thermoplastic composite materials, so the performance of the formed parts is lower than that of the parts made of continuous fiber thermoplastic composite materials, and it has certain requirements for the viscosity and thermal stability of the resin matrix; pultrusion forming and winding forming are simple to operate and easy to realize automation, but the equipment cost is high and the cross-sectional shape of the formed parts is limited; the laying forming process has high automation degree and high production efficiency, but it needs external heat source such as high temperature gas, infrared, laser, etc.; 3D printing forming is a layer-by-layer forming method, which has the characteristics of intelligence, automation and flexible design, but the forming speed is low, the forming precision is difficult to control, and it is difficult to process and form thermoplastic composite materials with high melting point of resin matrix. The above common thermoplastic composite processing and forming methods have certain limitations due to their own forming principles. Therefore, a method that is simple to operate, has low equipment cost, high production efficiency and can realize the forming and preparation of parts with complex profile is needed.

[0004] In recent years, some scholars have proposed new technical means for the additive manufacturing of thermoplastic composites. For example, the Chinese patent authorization document with publication number CN116922811B discloses a kind of fiber reinforced thermoplastic resin-based composite material friction additive manufacturing device and method, which includes resin rod extrusion mechanism and prepreg laying mechanism. In the resin rod extrusion mechanism, the shaft sleeve can be provided with a rod along the vertical direction and rotated synchronously with the rod around the vertical line, the lower end of the shaft sleeve can be heated by additive friction, and the softened end of the rod can flow along its radial direction and be laid on the additive layer, and the shaft sleeve can be moved upward relative to the rod under the driving of the support cylinder. In the prepreg laying mechanism, the prepreg entering between the support plate and the conveying belt is extruded by the support plate and the conveying belt, and the conveying belt brings the prepreg to the additive. The device of the invention can realize the friction additive of fiber reinforced thermoplastic composite material, avoid the generation of defects such as porosity and interlayer crack, and retain the good metallurgical connection effect of additive organization, so as to obtain high-precision and high-performance fiber reinforced thermoplastic composite structure. The lower end of the shaft sleeve is rubbed with the additive material to generate heat, the resin rod placed in the shaft sleeve is softened and extruded, and the prepreg is laid on the extruded resin additive layer to complete the additive. The difference between the present invention and the patent is that the additional resin rod is used as the additive raw material, and the resin matrix of the material itself at the interface of the prepreg is melted and molecular diffusion occurs by applying ultrasonic vibration to realize the combination. The Chinese patent authorization document with publication number CN114407351B discloses a kind of continuous fiber hybrid reinforced thermoplastic matrix composite material additive manufacturing equipment, which includes driving module, printing module and forming module; the power output end of the driving module is connected with the printing module; the continuous fiber mixing mechanism of the printing module is connected with the hybrid prepreg tape re-sending mechanism, the hybrid prepreg tape re-sending mechanism is connected with the rolling mechanism, and the rolling mechanism is arranged above the forming plate of the forming module; the forming plate of the forming module is arranged above the power output end of the driving mechanism. The technical problem of lack of hybrid fiber reinforced composite material equipment is solved. The invention realizes in-situ additive manufacturing of hybrid fiber reinforced composite material by mixing two kinds of prepreg tapes through the continuous fiber mixing mechanism, rolling and re-sending through the hybrid prepreg tape re-sending mechanism, and rolling printing on the forming plate through the rolling mechanism. The invention realizes the additive manufacturing of hybrid fiber reinforced thermoplastic composite material by heating and rolling. The invention uses heating plate and laser as heat source to heat and soften the resin matrix of thermoplastic composite material, while the present invention uses ultrasonic vibration as energy to heat the resin matrix of thermoplastic composite material due to high-frequency friction. SUMMARY

[0005] Invention purposes: Since the forming methods such as hot pressing forming, injection molding, pultrusion forming, winding forming, laying forming, 3D printing forming, etc. have certain limitations in the preparation of thermoplastic composite parts due to the limitations of their respective forming principles, the existing thermoplastic composite additive devices and methods mainly add resin matrix as additive raw material or add laser and heating plate as resin matrix softening heat source to realize additive. Therefore, the present application provides a method for preparing and forming a thermoplastic composite part containing a complex profile by layer-by-layer stacking with ultrasonic vibration as energy. Without the need for external heat source and filling resin, the resin matrix at the interface of the thermoplastic composite is caused to melt and soften and intermolecular diffusion occurs by applying ultrasonic vibration to achieve the purpose of additive. The forming performance of the additive part can be better controlled by adjusting the process parameters, and the pressure and vibration are only applied in the additive area, which has little effect on the material outside the additive area, and the process can be completed in a short time, effectively improving the forming speed, while the ultrasonic additive energy consumption is low, which can effectively save energy cost.

[0006] Technical scheme: In order to achieve the above invention purposes, the present application adopts the following scheme:

[0007] The method of ultrasonic additive thermoplastic composite mainly causes high-frequency friction between two layers of thermoplastic composite materials by applying ultrasonic load after the materials are compacted with a certain pressure, so as to generate heat. The matrix materials at the interface of the two layers of materials melt and intermolecular diffusion occurs under the action of heat and force coupling, and a firm connection is formed after cooling. On this basis, the combination between layers of materials is realized through the continuous additive process of point-line-surface, and then the preparation and forming of ultrasonic additive parts are realized through layer-by-layer stacking. The ultrasonic additive thermoplastic composite device mainly includes linear guide rail modules, a rotary table, an ultrasonic power supply, a transducer, an amplitude changer, and an ultrasonic additive tool head. Two linear guide rail modules can control the up-and-down movement of the spherical ultrasonic additive tool head along the Z direction, two linear guide rail modules control the movement of the spherical ultrasonic additive tool head along the Y direction, one linear guide rail module controls the movement of the ultrasonic additive tool head along the X direction, and the rotary table controls the rotation of the material around the X and Z directions, so as to ensure that the spherical tool head always moves along the normal direction of the profile of the material during the ultrasonic additive process. The ultrasonic power supply generates ultrasonic excitation and transmits it to the transducer, the transducer converts electrical energy into mechanical energy and amplifies it through the amplitude changer, and then transmits it to the spherical ultrasonic additive tool head. The spherical ultrasonic additive tool head continuously performs ultrasonic additive along the preset trajectory under the driving action of the X and Y direction linear guide rail modules, and rotates at high speed during the process to improve the ultrasonic additive energy and the uniformity of the energy.

[0008] The lower mold for placing the material to be added can contain multiple surface shape features, such as planes, inclined planes, circular arc surfaces, etc.

[0009] The method of ultrasonic wave additive thermoplastic composite based on the above device,

[0010] (1) By translation of the ultrasonic additive tool head and rotation of the material, the ultrasonic additive tool head is kept consistent with the normal direction at the position to be added, so that the contact position of the ultrasonic additive tool head and the material is always the lowest point of the ultrasonic additive tool head; the Z-direction linear guide rail module is controlled to press the ultrasonic additive tool head on the material surface with a certain preset pressure; the ultrasonic additive tool head is driven to rotate by the motor and the ultrasonic power supply is turned on to drive the transducer to produce mechanical vibration with a certain preset power, the amplitude of the mechanical vibration is amplified by the amplitude amplifier to drive the ultrasonic additive tool head to produce a preset ultrasonic vibration, and the ultrasonic vibration is continuously applied, during which friction is generated between the two layers of materials under the action of ultrasonic load, heat is generated at the interface of the two layers of materials due to high-frequency friction to a certain temperature, under the action of the temperature and the preset pressure, the matrix material in the thermoplastic composite material softens and produces intermolecular diffusion connection reaction, and after cooling, the materials can be closely attached.

[0011] (2) The ultrasonic additive tool head moves along the preset path for continuous addition, and when the ultrasonic additive tool head completes the addition of all positions of the current material along the preset path, the ultrasonic additive tool head is lifted along the positive direction of the Z-axis and the next layer of material is laid, and the above steps are repeated until a complete ultrasonic additive part is formed.

[0012] Advantages:

[0013] (1) The device for ultrasonic additive thermoplastic composite material provided by the application connects two layers of thermoplastic composite materials in a short time by using ultrasonic waves, the temperature at the material interface is low and easy to control, the heat effect of the material is small, and the preparation and forming of the ultrasonic additive thermoplastic composite part can be realized.

[0014] (2) The linear guide rail module can drive the ultrasonic additive tool head to move in X, Y and Z directions, thereby realizing continuous ultrasonic addition. While the ultrasonic additive tool head implements continuous ultrasonic addition along the preset path, it is driven to rotate at high speed by the motor, so as to improve the uniformity of ultrasonic addition energy and energy, and realize the forming and preparation of ultrasonic additive parts with high strength.

[0015] (3) The lower mold for laying the ultrasonic additive part can contain multiple shape features such as planes, inclined surfaces, arc surfaces, etc. During the additive process, the rotary table can drive the lower mold to rotate, so that the ultrasonic additive tool head is compatible with multiple shape features, and therefore the ultrasonic additive part with complex profile can be manufactured. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 is a schematic diagram of the overall device of the application;

[0017] Fig. 2 is a schematic diagram of the lower mold of the application; wherein: a-convex surface, b-concave surface, c-plane, d-inclined surface;

[0018] Fig. 3 is a schematic diagram of the ultrasonic head of the present application;

[0019] Fig. 4 is a schematic diagram of the primary coil of the present application; the inset is a cross-sectional view of the circled portion;

[0020] Fig. 5 is a schematic diagram of the ultrasonic additive trajectory of the present application;

[0021] Fig. 6 is a schematic diagram of the ultrasonic wave additive thermoplastic composite of the present application;

[0022] Fig. 7 is a schematic diagram of the rotary table structure and a schematic diagram of the rotation mode of the present application;

[0023] Fig. 8 is an SEM cross-sectional morphology diagram of the ultrasonic additive thermoplastic composite obtained in Example 1 of the present application after tensile testing; a large number of fibers are observed at the material cross section, and the bonding strength at the material interface is high, so the present application can be used to prepare high-strength parts.

[0024] Explanation of reference numerals: 1 - ultrasonic additive platform, 2 - rotary table, 3 - lower mold, 4 - ultrasonic head, 4-1 - transducer, 4-2 - amplitude rod, 4-3 - ultrasonic additive tool head, 4-4 - secondary coil, 5 - linear guide rail module, 6 - ultrasonic power supply, 7 - primary coil, 8 - upper layer of workpiece, 9 - lower layer of workpiece, 10 - ultrasonic vibration, 11 - region where molecular diffusion connection reaction of two-layer thermoplastic composite occurs. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions in the patent application, the technical solutions in the present application will be clearly and completely described below with reference to the drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0026] Referring to Fig. 1, the ultrasonic wave additive thermoplastic composite device comprises a linear guide rail module, a rotary table 2, an ultrasonic power supply 6, an ultrasonic head 4, a lower mold 3, and a primary coil 7; by controlling the translation of the ultrasonic head 4 and the rotation of the rotary table 2, the preparation of ultrasonic additive parts containing complex profile surfaces is realized.

[0027] The rotary table 2 is fixed on the ultrasonic additive platform 1, and the lower mold 3 is placed on the rotary table 2; the outer shape profile of the ultrasonic additive part is determined by the lower mold structure, and the outer shape profile of the lower mold can be a plane or a curved surface or a combination of a plane and a curved surface, so as to realize the additive process of the part containing a complex profile outer shape; as shown in Fig. 7, the rotary table 2 can drive the material to be processed to rotate around the X and Z axes.

[0028] Referring to FIG. 1, FIG. 3, the ultrasonic head 4 mainly comprises a transducer 4-1, a variable amplitude rod 4-2, an ultrasonic additive tool head 4-3 and a sub-edge coil 4-4. Among them, the transducer 4-1 is connected with the sub-edge coil 4-4 at one end and connected with the variable amplitude rod 4-2 at the other end (the diameters of the two connection ends are equal, and the connection position is located at the larger end of the variable amplitude rod, which ensures that the output quality of the ultrasonic signal is optimal), the original edge coil 7 is connected with the ultrasonic power supply 6, the ultrasonic additive tool head 4-3 is connected at the smaller end of the variable amplitude rod 4-2, and the working surface shape of the ultrasonic additive tool head can be a plane or a curved surface. After the power output, the transducer 4-1 drives the variable amplitude rod 4-2 to generate ultrasonic vibration, and the ultrasonic additive tool head 4-3 is driven by the variable amplitude rod 4-2 to perform ultrasonic vibration. In the ultrasonic additive process, the transducer 4-1, the variable amplitude rod 4-2 and the ultrasonic additive tool head 4-3 will make the two layers of materials on the workpiece on the lower mold tightly contact at a predetermined pressure, and due to the application of ultrasonic vibration 10, high-frequency friction is generated at the interface between the two layers of materials at the current additive position. The heat generated by friction makes the matrix material of the thermoplastic composite material soften and diffuse connection.

[0029] Specifically, by controlling the translation of the ultrasonic head 4 in the linear guide rail module 5 and the rotation of the rotary table 2, the movement of the ultrasonic additive tool and the rotation of the material are controlled.

[0030] The linear guide rail module is composed of guide rail modules for controlling the translation of the ultrasonic additive tool head 4 in X, Y and Z directions. Among them, two linear guide rail modules for controlling the Y direction movement (forward and backward movement) of the ultrasonic additive tool are horizontally placed on the ultrasonic additive platform 1, two linear guide rail modules for controlling the Z direction movement (up and down movement) are vertically fixed on the slider of the Y direction linear guide rail module, and the X direction movement (horizontal movement) is realized by the linear guide rail module fixed on the slider of the Z direction linear guide rail module; the ultrasonic additive tool is installed on the slider of the X direction linear guide rail module and can move horizontally along the slider; the slider of the X direction linear guide rail module moves up and down along the slider of the Y direction linear guide rail module, realizing the up and down movement of the ultrasonic additive tool. The rotary table is horizontally placed on the ultrasonic additive platform, which can control the rotation of the material around X and Z directions.

[0031] The method of ultrasonic additive thermoplastic composite material based on the ultrasonic additive thermoplastic composite material device described above, the steps are as follows:

[0032] (1) Determine the structure size of the lower mold 3 and the shape and size of the contact surface between the lower mold and the workpiece material. Determine the matrix material of the lower mold. Processing of the lower mold: process the lower mold to ensure the shape accuracy of the contact surface between the lower mold and the workpiece material. FIG. 2 is a structural schematic diagram of the lower mold obtained in this embodiment.

[0033] (2) Lay two layers of the material to be added on the surface of the lower mold 3, and move the ultrasonic head 4 to the starting position of the ultrasonic additive track (see FIG. 5). Control the Z-direction linear guide rail module to drive the ultrasonic head 4 to press on the surface of the workpiece with a certain pressure. Control the rotary table 2 to drive the workpiece (two layers of thermoplastic composite prepreg) to rotate, so that the ultrasonic additive tool head 4-3 is always located in the normal direction of the current additive position point during the additive process, so as to realize the preparation of the ultrasonic additive parts with complex profile.

[0034] (3) Control the ultrasonic head 4 to rotate at high speed by the motor, and turn on the ultrasonic power supply 6 to drive the transducer 4-1 on the ultrasonic head 4 to generate ultrasonic excitation. The ultrasonic vibration amplitude is amplified through the amplitude transformer 4-2, and the ultrasonic additive tool head 4-3 generates a preset ultrasonic vibration. The heat generated between the upper layer material 8 and the lower layer material 9 due to high-frequency friction reaches a certain temperature, and the matrix materials at the interface of the two layers of materials soften under the action of heat and force, and diffuse with each other (see FIG. 6). After cooling, a stable connection is formed.

[0035] During the ultrasonic additive process, the heat generated at the interface of the prepreg is affected by the ultrasonic additive process parameters and the materials, as shown in formulas (3) and (4).

[0036] Q = μ * P * v (3)

[0037] v = 2π * f * A (4)

[0038] Where Q is the power of friction heat, μ is the friction coefficient, P is the applied pressure, v is the relative vibration speed, f is the ultrasonic vibration frequency, and A is the ultrasonic vibration amplitude.

[0039] Therefore, the factors affecting the ultrasonic additive results in the ultrasonic additive thermoplastic composite process include ultrasonic vibration parameters (such as ultrasonic vibration frequency and amplitude), material parameters (such as matrix material and shape complexity), track parameters (such as preset increment value and ultrasonic head moving direction), and process parameters (such as the pressure of the ultrasonic head on the material and the power output of the power supply).

[0040] (4) The linear guide rail module 5 controls the ultrasonic head 4 to move along the pre-set ultrasonic additive track in an S-shaped detour. First, the X-direction linear guide rail module controls the ultrasonic head 4 to move along the positive direction of the X-axis for continuous ultrasonic additive, and when the ultrasonic head 4 completes the ultrasonic additive of the current row of materials, the Y-direction linear guide rail module controls the ultrasonic head 4 to move along the positive direction of the Y-axis by a preset increment, and the X-direction linear guide rail module controls the ultrasonic head 4 to move along the negative direction of the X-axis for continuous ultrasonic additive. Repeat the above steps until the ultrasonic head 4 completes the entire track of the current layer of materials.

[0041] (5) When the ultrasonic head 4 walks through all the trajectories of the current additive layer, the ultrasonic head 4 is lifted along the positive direction of the Z axis, the next layer of the material to be added is laid, and steps (4) and (5) are repeated until the manufacturing of the whole ultrasonic additive part is completed.

[0042] Example 1

[0043] In this embodiment, the shape accuracy of the lower mold and the material contact surface is controlled to be ±0.01 mm. During the ultrasonic additive process, the ultrasonic additive tool head is always kept in the normal direction of the current additive position to ensure that the preset pressure and the ultrasonic load can be applied to the complex profile surface.

[0044] The types of the reinforcing phase and the resin matrix in each layer of the prepreg need to be the same, but the reinforcing phase structure can change, such as unidirectional fiber, woven fiber, mixed fiber, etc., and the laying angle (0°, 45°, 90°, etc.) and the laying order of the prepreg can also change. In this embodiment, carbon fiber reinforced polyether ether ketone unidirectional prepreg is used as the additive material, and the additive is carried out at a 0° layup angle. According to formulas 3 and 4, the performance of the finished product is affected by the ultrasonic additive process parameters, the greater the frequency, amplitude, and pressure of the ultrasonic additive, the more heat generated at the material interface, when the heat reaches the melting point of the polyether ether ketone resin matrix, it can melt and flow and form a tight fit between the materials, but too much heat will cause thermal decomposition of the resin matrix material, therefore, in this embodiment, a pressure of 100 N, a frequency of 20 kHz, and an amplitude of 20 μm are selected, and the interlayer bonding strength of the finished product obtained under these parameters is higher.

[0045] At the initial position of the preset trajectory, the ultrasonic head moves along the negative direction of the Z axis, and the ultrasonic additive tool head is pressed on the material to be added with a pressure of 100 N, the ultrasonic power is turned on and the output power is adjusted to 2600 W, the ultrasonic additive tool head at the front end of the ultrasonic head generates ultrasonic vibration with a frequency of 20 kHz and an amplitude of 20 μm, so that the material to be added generates high-frequency friction, so that the matrix material in the thermoplastic composite material softens at this temperature and diffuses between molecules under the joint action of pressure, and a relatively firm connection is formed at the current additive position.

[0046] The ultrasonic head moves along the positive direction of the X axis at a speed of 10 mm / s from the initial position, and when the ultrasonic addition of all positions in the current X direction is realized, the ultrasonic head moves along the Y direction by a preset increment (for example, 10 mm), and the above ultrasonic addition process is carried out along the negative direction of the X axis. During the addition process, when the ultrasonic head moves to the area of other contour features (for example, from the inclined surface to the circular arc surface), the workbench will ensure that the ultrasonic head is always in the normal direction of the current addition position through the rotation movement around the X axis. When the ultrasonic head walks through the preset track of the current layer of material, the ultrasonic head is lifted, and the next layer of material to be added is laid, the ultrasonic head returns to the initial position again, and the above process is repeated to carry out the ultrasonic addition process of the layer of material, until the complete ultrasonic addition part is formed.

[0047] The above description of various embodiments of the application is provided to those skilled in the art for the purpose of describing the application. It is not intended to be exhaustive or to be limited to a single disclosed embodiment. As mentioned above, various alternatives or variations of the present application will be apparent to those skilled in the art in light of the above teachings. Thus, while certain embodiments have been discussed, other embodiments will be obvious to those of ordinary skill in the art and can be made without departing from the spirit and scope of the application. The present application is intended to include all such alternatives, modifications and variations as falling within the scope of the present application. Although the application has been described by way of example with reference to certain embodiments thereof, it is clear that modifications and improvements will occur to others skilled in the art who are not departing from the spirit and scope of the application. It is intended that the following claims encompass any and all such modifications and improvements.

Claims

1. An apparatus for ultrasonic additive thermoplastic composites, characterized by, It comprises: Linear guide rail module (5), rotary table (2), ultrasonic power supply (6), ultrasonic head (4), lower mold (3), primary coil (7); the linear guide rail module is fixed symmetrically on the ultrasonic additive platform (1), the rotary table (2) is fixed on the ultrasonic additive platform (1) below the linear guide rail module, the lower mold (3) is placed on the rotary table (2); the ultrasonic head (4) is movably fixed on the linear guide rail module, the preparation of the ultrasonic additive parts containing complex profile is realized by controlling the translation of the ultrasonic head (4) in three-dimensional space and the rotation of the rotary table (2); the primary coil (7) is coaxially fixed on the linear guide rail module with the ultrasonic head (4).

2. The apparatus of ultrasonic additive thermoplastic composite material according to claim 1, characterized in that, The workpiece contour is determined by the lower mold structure, and the contour of the lower mold is a plane or a curved surface or a combination of a plane and a curved surface, so as to realize the additive of the parts containing complex contour; the rotary table drives the workpiece to rotate around the X and Z axes.

3. The apparatus of claim 1, wherein, The ultrasonic head (4) comprises a transducer (4-1), a variable amplitude rod (4-2), an ultrasonic additive tool head (4-3) and a secondary coil (4-4); wherein one end of the transducer is connected with the secondary coil (4-4), the other end is connected with the variable amplitude rod (4-2), the primary coil (7) is connected with the ultrasonic power supply (6); the ultrasonic additive tool head (4-3) is connected to the smaller end of the variable amplitude rod (4-2); after the ultrasonic power supply outputs energy, the transducer (4-1) drives the variable amplitude rod (4-2) to generate ultrasonic vibration, and the ultrasonic additive tool head (4-3) is driven by the variable amplitude rod (4-2) to generate ultrasonic vibration; during the ultrasonic additive process, the transducer (4-1), the variable amplitude rod (4-2) and the ultrasonic additive tool head (4-3) make the workpiece on the lower mold tightly contact with a preset pressure, and due to the application of ultrasonic vibration, high frequency friction is generated at the interface between the workpieces at the current additive position, the heat generated by friction makes the matrix material of the thermoplastic composite material soften and diffuse.

4. The apparatus of claim 3, wherein, During the ultrasonic additive process, the heat generated by friction is shown in formula (3) and formula (4): Q=μ*P*v (3) v=2π*f*A (4) Wherein Q is the power of friction heat, μ is the friction coefficient, P is the applied pressure, v is the relative vibration speed, f is the ultrasonic vibration frequency, and A is the ultrasonic vibration amplitude.

5. The apparatus of claim 3, wherein, The working surface shape of the ultrasonic additive tool head is a plane or a curved surface; the connection end of the transducer and the variable amplitude rod (4-2) has equal diameters.

6. The apparatus of claim 1, wherein, The linear guide rail module comprises guide rail modules for controlling the translation of the ultrasonic head (4) in three directions X, Y and Z; wherein two linear guide rail modules for controlling the forward and backward movement of the ultrasonic additive tool are horizontally placed on the ultrasonic additive platform (1), two linear guide rail modules for controlling the upward and downward movement are vertically fixed on the sliders of the aforementioned forward and backward movement linear guide rail modules, the horizontal movement is realized by the linear guide rail modules fixed on the sliders of the aforementioned upward and downward movement linear guide rail modules; the ultrasonic additive tool is movably installed on the slider of the horizontal movement linear guide rail module and can move horizontally along the slider; the slider of the horizontal movement linear guide rail module moves up and down along the slider of the forward and backward movement linear guide rail module, thereby realizing the upward and downward movement of the ultrasonic additive tool.

7. A method of ultrasonic additive thermoplastic composite of the apparatus of ultrasonic additive thermoplastic composite according to claim 1, characterized in that, After the two layers of thermoplastic composite materials on the workpiece are compacted under a certain pressure, the ultrasonic load is applied to cause high-frequency friction between the materials to generate heat, and the matrix material at the interface of the workpiece is melted and diffused under the action of thermal and mechanical coupling, and after cooling, the close fit between the material layers is formed, and on this basis, the preparation and forming of the ultrasonic additive parts are realized by layer-by-layer stacking.

8. The method of ultrasonic additive thermoplastic composites of claim 7, wherein, The specific steps are as follows: (1) When performing initial additive manufacturing, first place the lower mold (3) on the rotary table, and then place the workpiece, which is two layers of thermoplastic composite prepreg, on the lower mold (3) in an orderly manner. Move the ultrasonic additive tool head in the negative direction of the Z axis so that the ultrasonic additive tool head (4-3) is tightly pressed against the surface of the workpiece and is located at the starting point of the ultrasonic additive trajectory. (2) Rotate the lower mold (3) and the workpiece by the rotary table, and realize that the tangent direction of the surface of the workpiece at the current additive position during the ultrasonic additive process is always perpendicular to the ultrasonic additive tool head in the vertical direction by the translation of the ultrasonic additive tool head and the rotation of the workpiece. Turn on the ultrasonic power supply and control the ultrasonic additive tool head to rotate at high speed by the motor. The transducer generates ultrasonic excitation, the amplitude of the ultrasonic vibration is amplified by the amplitude transformer, and then the ultrasonic additive tool head is transmitted to perform ultrasonic additive manufacturing. The matrix material at the interface of the two layers of thermoplastic composite materials is fused due to the heat generated by high-frequency friction under the action of ultrasonic load, thereby realizing the additive process. The ultrasonic additive tool head continuously performs ultrasonic additive manufacturing along the preset trajectory until the entire trajectory of the current two layers of materials is completed, then stop the rotation of the ultrasonic additive tool head and turn off the ultrasonic power supply. (3) After the additive manufacturing of the two layers of materials is completed, lift the ultrasonic additive tool head in the positive direction of the Z axis, lay the next layer of thermoplastic composite prepreg, and repeat the above steps to stack layer by layer until the desired shape is formed.

9. The method of ultrasonic additive thermoplastic composite material according to claim 7 or 8, characterized in that, The reinforcing phase and the resin matrix of the two layers of thermoplastic composite prepreg are the same, but the reinforcing phase structure can be selected from any one of unidirectional fibers, woven fibers and hybrid fibers, and the layup angle and layup sequence of the prepreg can be adjusted accordingly. The layup angle can be 0°, 45° or 90°.

10. The method of ultrasonic additive thermoplastic composites of claim 8, wherein, The ultrasonic additive trajectory is a zigzag back-and-forth movement.

Images