Thermoplastic composite material ultrasonic welding method and welding device based on material physical property

Abstract

The invention provides a thermoplastic composite material ultrasonic welding method and welding device based on material physical properties, and the thermoplastic composite material ultrasonic welding method based on material physical properties comprises the following steps: arranging thermoplastic composite material layers on to-be-welded surfaces of a first thermoplastic composite material part and a second thermoplastic composite material part, wherein the melting point of the thermoplastic composite material layer is lower than that of the first thermoplastic composite material part and that of the second thermoplastic composite material part; the welding areas of the first thermoplastic composite material part and the second thermoplastic material part are fixed in a lap joint mode, an energy conduction item is arranged between the first thermoplastic composite material part and the second thermoplastic material part, and ultrasonic welding is conducted on the welding areas; and after ultrasonic welding is completed, pressure is applied to the welding area till the welding area is cooled to the room temperature, and solidification is completed. Ultrasonic welding can be completed under the condition that the surface quality of the workpiece is guaranteed, the appearance and internal quality of the workpiece are guaranteed, and high-quality welding of the thermoplastic composite workpiece is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic welding, and more particularly to a method and device for ultrasonic welding of thermoplastic composite materials based on material properties. Background Art

[0002] Currently, when ultrasonically welding thermoplastic composite parts, the energy conduction term at the weld interface approaches the melting point of the base material of the welded part. During ultrasonic welding, the mechanical energy generated by ultrasonic vibrations generates heat, melting the energy conduction term at the weld interface with the resin on the part's surface. Upon cooling, the thermoplastic resin resolidifies, achieving the desired weld.

[0003] A drawback of the aforementioned ultrasonic welding method for thermoplastic composite parts is that, in ultrasonic welding, ultrasonic energy gradually attenuates as part thickness increases, with the maximum energy received at the interface between the weld head and the part. Because the energy conductor at the weld interface approaches the melting point of the part's base material, when energy absorption at the weld interface causes the conductor to melt, the material at the contact point between the part's surface and the weld head often also melts, causing surface and internal quality issues and compromising product performance. Summary of the Invention

[0004] (1) Technical issues to be resolved The technical problem to be solved by the present invention is that existing thermoplastic composite material parts are prone to surface and internal quality problems during ultrasonic welding.

[0005] (2) Technical solution To achieve the above object, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a thermoplastic composite ultrasonic welding method based on material properties, for welding a first thermoplastic composite part to a second thermoplastic material part, comprising the following steps: S1. Connecting and disposing thermoplastic composite layers on the surfaces to be welded of the first thermoplastic composite part and the second thermoplastic composite part, respectively, wherein the melting point of the thermoplastic composite layer is lower than the melting point of the first thermoplastic composite part and the second thermoplastic composite part, and the stiffness of the thermoplastic composite layer is lower than the stiffness of the first thermoplastic composite part and the second thermoplastic composite part; S2. Overlap and secure the welding areas of the first thermoplastic composite part and the second thermoplastic composite part, and provide an energy conductor between the first thermoplastic composite part and the second thermoplastic composite part, wherein the material of the energy conductor is the same as the resin system of the thermoplastic composite layer, and the first thermoplastic composite part is located on the side closest to the ultrasonic welding equipment; S3, start the ultrasonic welding equipment to perform ultrasonic welding on the welding area; S4. After ultrasonic welding is completed, pressure is applied to the welding area until the welding area cools to room temperature and solidification is completed.

[0006] Preferably, the thermoplastic composite material layer is fixedly connected to the surface to be welded of the first thermoplastic composite material part by hot pressing.

[0007] Preferably, the energy conducting item is spot-welded to the welding surface of the first thermoplastic composite part, or the energy conducting item is spot-welded to the welding surface of the second thermoplastic material part.

[0008] Preferably, the material of the first thermoplastic composite part and the second thermoplastic material part is continuous fiber reinforced polyetheretherketone, the material of the thermoplastic composite layer is continuous fiber reinforced low-melting-point polyaryletherketone, and the energy conducting item material is low-melting-point polyaryletherketone.

[0009] In a second aspect, the present invention also provides a welding device for implementing the ultrasonic welding method of thermoplastic composite materials based on material properties described in any one of the above technical solutions, the welding device comprising a workbench, a first clamping member, a second clamping member, an ultrasonic welding device, and a consolidation unit; the first clamping member is used to clamp and fix the first thermoplastic composite part to the workbench; the second clamping member is used to clamp and fix the second thermoplastic composite part to the workbench; the ultrasonic welding device is used to ultrasonically weld the welding area; and the consolidation unit is used to apply pressure to the welding area after the ultrasonic welding is completed.

[0010] Preferably, the first clamping member includes a first fastener, a first pressure plate and a gasket; the gasket is arranged between the workbench and the first thermoplastic composite part, the first pressure plate is arranged on the side of the first thermoplastic composite part away from the gasket, and the first fastener fastens the first pressure plate, the first thermoplastic composite part, the gasket and the workbench.

[0011] Preferably, the second clamping member includes a second pressing plate and a second fastener, the second pressing plate is arranged on a side of the second thermoplastic composite part away from the workbench, and the second fastener fastens the second pressing plate and the second thermoplastic composite part.

[0012] Preferably, it also includes an infrared temperature measurement component, which is used to measure the welding temperature of the welding area.

[0013] (3) Beneficial effects The above technical solution of the present invention has at least the following advantages: In the present invention, a thermoplastic composite material layer is provided in connection with the surfaces to be welded of the first thermoplastic composite part and the second thermoplastic composite part. When the parts are ultrasonically welded, since the melting point of the thermoplastic composite material layer on the welding surface is lower than the melting points of the first thermoplastic composite part and the second thermoplastic composite part, when the resin at the welding interface melts, the contact interface temperature between the welding head and the first thermoplastic composite part does not reach the melting point, so that a temperature gradient exists between the melting point at the welding interface and the melting point of the workpiece matrix material. Therefore, ultrasonic welding can be completed while ensuring the surface quality of the workpiece. In addition, a gradient exists between the stiffness at the welding interface and the stiffness of the workpiece matrix material, thereby ensuring the appearance and internal quality of the workpiece and achieving high-quality welding of thermoplastic composite parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 It is a schematic flow chart of a method for ultrasonic welding of thermoplastic composite materials based on material properties provided in an embodiment of the present invention.

[0016] Figure 2 Schematic diagram of the overlapped state of a first thermoplastic composite material part and a second thermoplastic material part provided by an embodiment of the present invention.

[0017] Figure 3 This is one of the structural schematic diagrams of the welding device provided in an embodiment of the present invention.

[0018] Figure 4 This is the second structural schematic diagram of the welding device provided in an embodiment of the present invention.

[0019] The reference numerals in the figures are: 1. Workbench; 21. First fastener; 22. First pressure plate; 23. Gasket; 31. Second pressure plate; 32. Second fastener; 4. Ultrasonic welding equipment; 5. Consolidation unit; 6. Infrared temperature measurement component; 10. First thermoplastic composite part; 20. Second thermoplastic composite part; 31. Thermoplastic composite layer; 40. Energy conduction item. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] It should be noted that when an element is referred to as being “fixed to” or “disposed on” another element, it may be directly located on the other element or indirectly located on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0022] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating relative importance or the number of technical features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined. The following is a more detailed description of the specific implementation of the present invention in conjunction with specific embodiments: like Figures 1 to 4 As shown, the present invention also provides a welding device for implementing any one of the thermoplastic composite material ultrasonic welding methods based on material properties in the above embodiments. The welding device includes a workbench 1, a first clamping member, a second clamping member, an ultrasonic welding device 4 and a consolidation unit 5; the first clamping member is used to clamp and fix the first thermoplastic composite part 10 on the workbench 1; the second clamping member is used to clamp and fix the second thermoplastic composite part 20 on the workbench 1; the ultrasonic welding device 4 is used to ultrasonically weld the welding area; and the consolidation unit 5 is used to apply pressure to the welding area after the ultrasonic welding is completed.

[0024] In one embodiment, the first clamping member includes a first fastener 21, a first pressure plate 22, and a gasket 23; the gasket 23 is arranged between the workbench 1 and the first thermoplastic composite part 10, the first pressure plate 22 is arranged on the side of the first thermoplastic composite part 10 away from the gasket 23, and the first fastener 21 fastens the first pressure plate 22, the first thermoplastic composite part 10, the gasket 23, and the workbench 1.

[0025] In one embodiment, the second clamping member includes a second pressing plate 31 and a second fastener 32. The second pressing plate 31 is arranged on a side of the second thermoplastic composite part 20 away from the workbench 1, and the second fastener 32 fastens the second pressing plate 31 and the second thermoplastic composite part 20.

[0026] In one embodiment, an infrared temperature measuring component 6 is further included, and the infrared temperature measuring component 6 is used to measure the welding temperature of the welding area.

[0027] An embodiment of the present invention further provides a thermoplastic composite ultrasonic welding method based on material properties, which is used to weld a first thermoplastic composite part 10 to a second thermoplastic material part 20, comprising the following steps: S1. Connecting and disposing a thermoplastic composite layer 30 on the surfaces to be welded of the first thermoplastic composite part 10 and the second thermoplastic composite part 20, respectively. The melting point of the thermoplastic composite layer 30 is lower than the melting points of the first thermoplastic composite part 10 and the second thermoplastic composite part 20, and the stiffness of the thermoplastic composite layer 30 is lower than the stiffness of the first thermoplastic composite part 10 and the second thermoplastic composite part 20. S2. An energy conductor 40 is provided between the first thermoplastic composite part 10 and the second thermoplastic composite part 20, and the welding regions of the first thermoplastic composite part 10 and the second thermoplastic composite part 20 are overlapped and fixed. The material of the energy conductor 40 is the same resin system as that of the thermoplastic composite layer 30. The first thermoplastic composite part 10 is located near the ultrasonic welding device 4. S3, start the ultrasonic welding equipment 4 to perform ultrasonic welding on the welding area; S4. After ultrasonic welding is completed, pressure is applied to the welding area until the welding area cools to room temperature and solidification is completed.

[0028] In one embodiment, the thermoplastic composite material layer 30 is fixedly connected to the surfaces to be welded of the first thermoplastic composite material part 10 and the second thermoplastic material part 20 by hot pressing.

[0029] In one embodiment, the energy directing item 40 is spot-welded to the welding surface of the first thermoplastic composite part 10 , or the energy directing item 40 is spot-welded to the welding surface of the second thermoplastic composite part 20 .

[0030] In one embodiment, the first thermoplastic composite part 40 and the second thermoplastic composite part 20 are made of continuous fiber-reinforced polyetheretherketone (PEEK), the thermoplastic composite layer 30 is made of continuous fiber-reinforced low-melting-point polyaryletherketone (PAREK), and the energy conducting element 40 is made of low-melting-point PAEK. PAEK has greater material rigidity than PAEK.

[0031] The following are specific embodiments provided in this application: The thermoplastic composite single lap joint structure to be produced is as follows Figure 2As shown. This single-lap joint structure consists of a first thermoplastic composite part 10 and a second thermoplastic composite part 20. The thickness of the first thermoplastic composite part 10 and the second thermoplastic composite part 20 are both 3 mm. The length of the welding area is 25 mm and the width is 25 mm. The first thermoplastic composite part 10 and the second thermoplastic composite part 20 are continuous fiber reinforced polyetheretherketone with a melting point range of (340-345) ° C. The thermoplastic composite layer 30 is continuous fiber reinforced low-melting-point polyaryletherketone with a melting point range of (330-340) ° C. The material of the energy conductor 40 used for welding is low-melting-point polyaryletherketone with a melting point range of (330-340) ° C.

[0032] The ultrasonic welding forming steps are: Part pretreatment: A layer of continuous fiber reinforced low-melting-point polyaryletherketone prepreg (thermoplastic composite layer 30) is laid on the surfaces to be welded of the first thermoplastic composite part 10 and the second thermoplastic composite part 20 by spot welding. A hot press is used to consolidate the continuous fiber reinforced low-melting-point polyaryletherketone prepreg (thermoplastic composite layer 30) on the surfaces of the first thermoplastic composite part 10 and the second thermoplastic composite part 20.

[0033] Energy guiding item placement: Use a caliper to measure the size of the welding area, cut the energy guiding item according to the size of the welding area, and fix the cut energy guiding item 40 on the welding surface of the first thermoplastic composite part 10 and the second thermoplastic composite part 20 by spot welding.

[0034] Part positioning: The first thermoplastic composite part 10 and the second thermoplastic composite part 20 are positioned in the same direction as the first thermoplastic composite part 10 and the second thermoplastic composite part 20. Figure 2 After being overlapped and assembled in the illustrated manner, the parts are placed on a workbench. A gasket 23 is placed under the first thermoplastic composite part 10. The first pressing plate 22 and the first fastener 21 are used to secure the first thermoplastic composite part 10 to the workbench 1. The second pressing plate 31 and the second fastener 32 are used to secure the second thermoplastic composite part 20 to the workbench 1. In the operation interface, the welding head of the ultrasonic welding device 4 is lowered, the workbench 1 is moved, and the positions of the first thermoplastic composite part 10 and the second thermoplastic composite part 20 are adjusted to ensure that the effective welding area of the welding head covers the welding area of the parts, completing the part positioning.

[0035] Ultrasonic welding: The welding pressure and amplitude are set in the operation interface of the ultrasonic welding device 4. After the settings are completed, the ultrasonic welding device 4 is started and the temperature of the welding interface is monitored by the infrared temperature measuring device 6. During the process, the interface temperature reaches a maximum of 336°C, and the ultrasonic welding process is completed.

[0036] Consolidation after welding: After welding is completed, move the welding head so that the consolidation unit 5 applies a pressure of 500N on the welding area and maintains the pressure until the infrared temperature measuring device 6 shows that the interface temperature drops to room temperature, then release the pressure to complete the consolidation.

[0037] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A thermoplastic composite ultrasonic welding method based on material properties, used for welding a first thermoplastic composite part to a second thermoplastic material part, characterized in that: The following steps are involved: S1. Disposing a thermoplastic composite layer on surfaces of a first thermoplastic composite part and a second thermoplastic composite part to be welded, wherein the melting point of the thermoplastic composite layer is lower than the melting points of the first thermoplastic composite part and the second thermoplastic composite part, and the stiffness of the thermoplastic composite layer is lower than the stiffness of the first thermoplastic composite part and the second thermoplastic composite part; S2. Overlap and secure the welding areas of the first thermoplastic composite part and the second thermoplastic composite part, and provide an energy conductor between the first thermoplastic composite part and the second thermoplastic composite part, wherein the material of the energy conductor is the same as the resin system of the thermoplastic composite layer, and the first thermoplastic composite part is located on the side closest to the ultrasonic welding equipment; S3, start the ultrasonic welding equipment to perform ultrasonic welding on the welding area; S4. After ultrasonic welding is completed, pressure is applied to the welding area until the welding area cools to room temperature and solidification is completed.

2. The ultrasonic welding method for thermoplastic composite materials based on material properties according to claim 1, characterized in that: The thermoplastic composite material layers are respectively fixedly connected to the surfaces to be welded of the first thermoplastic composite material part and the second thermoplastic composite material part by hot pressing.

3. The ultrasonic welding method for thermoplastic composite materials based on material properties according to claim 1, characterized in that: The energy conducting item is spot-welded to the welding surface of the first thermoplastic composite part, or the energy conducting item is spot-welded to the welding surface of the second thermoplastic material part.

4. The ultrasonic welding method for thermoplastic composite materials based on material properties according to claim 1, characterized in that: The first thermoplastic composite material part and the second thermoplastic material part are made of continuous fiber reinforced polyetheretherketone, the thermoplastic composite material layer is made of continuous fiber reinforced low-melting-point polyaryletherketone, and the energy conducting material is low-melting-point polyaryletherketone.

5. A welding device, characterized in that: For implementing the ultrasonic welding method of thermoplastic composite materials based on material properties according to any one of claims 1 to 4, the welding device comprises: Workbench; a first clamping member, used for clamping and fixing the first thermoplastic composite part on the workbench; a second clamping member, used for clamping and fixing the second thermoplastic composite part on the workbench; Ultrasonic welding equipment, used for ultrasonic welding the welding area; Consolidation unit, used to apply pressure to the weld area after ultrasonic welding is completed.

6. The welding device according to claim 5, wherein: The first clamping member includes a first fastener, a first pressure plate and a gasket; the gasket is arranged between the workbench and the first thermoplastic composite part, the first pressure plate is arranged on the side of the first thermoplastic composite part away from the gasket, and the first fastener fastens the first pressure plate, the first thermoplastic composite part, the gasket and the workbench.

7. The welding device according to claim 5, wherein: The second clamping member includes a second pressing plate and a second fastener. The second pressing plate is arranged on a side of the second thermoplastic composite part away from the workbench. The second fastener fastens the second pressing plate and the second thermoplastic composite part.

8. The welding device according to claim 5, wherein: It also includes an infrared temperature measurement component, which is used to measure the welding temperature of the welding area.

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