Large scale ultrasonic plastic welding system

Abstract

The application discloses a large-size ultrasonic plastic welding system, which is sequentially connected by an ultrasonic transducer, a composite amplitude transformer and a tool head, the ultrasonic transducer is sequentially connected by a metal front cover plate, a piezoelectric ceramic crystal stack and a metal rear cover plate, the composite amplitude transformer is connected by a metal conical section and a metal cylindrical section, and the tool head is a metal cuboid, wherein, a periodic fan-shaped column hole is formed on an XY plane of the metal cuboid, surface grooves are formed on the XY plane, an XZ plane and a YZ plane respectively and form an acoustic surface structure, and through air grooves are formed on the XZ plane and the YZ plane respectively and form a topological defect structure. The application constructs the acoustic surface structure on each plane of the tool head, constructs a near-periodic phononic crystal structure and constructs the topological defect structure, thereby greatly improving the displacement amplitude of a radiation surface of the welding system and the uniformity of the amplitude distribution, improving the welding efficiency and precision of the welding system, and being suitable for the plastic welding field.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic welding technology, and specifically relates to a large-size ultrasonic plastic welding system. Background Technology

[0002] In recent decades, the demand for plastic products has been expanding, and they are widely used in all sectors of human life and the national economy. Ultrasonic plastic welding, due to its unparalleled advantages, has become the mainstream method for joining plastic components. The quality of ultrasonic plastic welding is greatly influenced by the performance of the ultrasonic welding system, welding process parameters, and the design of the weldment. However, in practical applications, some factors, such as the design of the weldment and the ambient temperature, are generally fixed, leaving little room for improvement. Improving the quality of ultrasonic plastic welding can be achieved by improving the performance of the ultrasonic welding system. There are many indicators for evaluating the performance of an ultrasonic plastic welding system, the most important of which are: (1) Amplitude gain: The amplitude output of the transducer in the ultrasonic plastic welding system, the amplification factor of the amplitude transformer, and the amplitude gain of the tool head itself play a decisive role in the amplitude output of the tool head's radiating surface. Studies have shown that at a given ultrasonic frequency, each type of plastic weldment has an optimal amplitude range. Within a suitable range, increasing the output amplitude gain of the tool head can improve the welding strength and shorten the welding time. However, if the amplitude is too large, exceeding the required amplitude, it is easy to cause over-welding and burn the weldment. If the amplitude is too small, failing to reach the required amplitude, the weldment will be difficult to melt, resulting in insufficient welding.

[0003] (2) Uniformity of amplitude distribution on the welding surface: also known as uniformity of longitudinal displacement distribution on the radiating surface, its quality directly affects the effective transmission of ultrasonic energy. If the uniformity of longitudinal displacement distribution on the radiating surface of the tool head is poor, it is easy to cause uneven transmission of vibration energy, resulting in local overflow or missing welds in the weldment, which seriously affects the quality of ultrasonic plastic welding. Therefore, the uniformity of amplitude distribution on the radiating surface of the tool head is particularly important for weldments with high appearance requirements and precise structure.

[0004] In practical ultrasonic plastic welding, to ensure efficient and stable energy transmission and output, the ultrasonic plastic welding system requires a uniform displacement amplitude distribution on its radiating surface to achieve high efficiency and reliability. However, for larger workpieces, large-sized tool heads are typically used to improve welding efficiency. These tool heads are susceptible to lateral vibrations in the length or width directions during welding, leading to uneven amplitude distribution on the tool head's radiating surface. This results in inconsistent energy transfer to the workpiece surface, potentially causing localized overflow or missed welds, affecting welding quality. Conversely, smaller amplitudes can lead to missed welds or insufficient weld strength. Therefore, effective vibration control methods are necessary to suppress harmful lateral vibrations in large-size ultrasonic plastic welding systems. Based on this, a large-size ultrasonic plastic welding system with high amplitude gain and uniform amplitude distribution on the welding surface needs to be proposed.

[0005] For a long time, research on large-size ultrasonic plastic welding systems by ultrasonic engineers has mainly focused on three aspects: 1) Analysis Methods for Coupled Vibrations. Currently, there are many methods for analyzing and designing coupled vibrations in large-size ultrasonic plastic welding systems, such as the adjoint method, Rayleigh energy method, and apparent elasticity method. Among them, the apparent elasticity method is widely used due to its simplicity and clear physical meaning, especially when analyzing relatively regular-shaped, ungrooved vibrating bodies, where it can yield satisfactory results. However, for large-size vibrating bodies with relatively complex shapes and multiple grooves / holes, the analysis and calculation process becomes very complex and may even produce significant errors. Therefore, it is necessary to provide new and more effective supporting theories for the analysis and design of large-size, structurally complex vibrating bodies with multiple grooves / holes. 2) Vibration control methods for large-size ultrasonic plastic welding systems. Currently, commonly used methods for controlling coupled vibration include slotting / holeing, adding elastic components, creating slits, and secondary design. These methods can improve the performance of high-power ultrasonic transducer systems to some extent. However, the determination of the size, location, and number of slots / holes / slits mainly relies on the developer's practical experience and simulation calculations, lacking effective theoretical basis. 3) Methods for suppressing harmful vibrations in large-size ultrasonic plastic welding systems. This method utilizes the band gaps of periodic phonon crystal slots and holes arranged in a specific lattice pattern on the vibrating body to suppress and attenuate harmful vibrations, thereby improving the uniformity of amplitude distribution at the system's radiating end face to some extent. However, the presence of periodic phonon crystal slots and holes inevitably alters the system's structural properties such as strength, stiffness, and modal characteristics, thus affecting the system's resonant frequency, radiated acoustic power, and operating bandwidth.

[0006] A summary of current research findings reveals that coupled vibration analysis is complex and prone to significant errors in systems with irregular shapes or numerous openings. Vibration control methods rely heavily on developers' practical experience and simulation calculations to determine the size, location, and number of slots / holes / slits, lacking a strong theoretical basis. While vibration suppression methods improve coupled vibration, they can negatively impact other performance characteristics. Each method has its limitations; therefore, to better meet the practical engineering needs of large-scale ultrasonic plastic welding systems, new and more effective optimization methods need to be explored. Summary of the Invention

[0007] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a large-size ultrasonic plastic welding system. This welding system constructs an acoustic surface structure by creating surface grooves on each plane of the tool head, constructs a near-periodic phonon crystal structure by creating periodic fan-shaped cylindrical holes on the XY plane, and constructs a topological defect structure by creating air grooves on the XZ and YZ planes respectively. This significantly improves the displacement amplitude and amplitude distribution uniformity of the welding system's radiation surface, thereby improving the welding efficiency and accuracy, and solving the problem of poor welding quality caused by uneven amplitude in large-size ultrasonic plastic welding systems.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a large-size ultrasonic plastic welding system, characterized in that it is composed of an ultrasonic transducer, a composite amplitude transformer and a tool head connected in sequence. The ultrasonic transducer is composed of a metal front cover plate, a piezoelectric ceramic crystal stack and a metal rear cover plate connected in sequence. The composite amplitude transformer is composed of a metal conical section and a metal cylindrical section connected in sequence. The tool head is a metal cuboid, wherein the metal cuboid has m rows × n columns of periodic fan-shaped cylindrical holes parallel to the Z-axis on the XY plane. Surface grooves are formed on the XY plane, XZ plane and YZ plane respectively to form an acoustic surface structure. Through air grooves are formed on the XZ plane and YZ plane respectively to form a topological defect structure.

[0009] The aforementioned large-size ultrasonic plastic welding system is characterized in that both the metal front cover and the metal rear cover are cylindrical, and the front end face of the piezoelectric ceramic crystal stack is connected to the rear end face of the metal rear cover and the rear end face is connected to the front end face of the metal front cover.

[0010] The aforementioned large-size ultrasonic plastic welding system is characterized in that the metal cylindrical section is connected to the rear end face of the metal front cover plate, and the metal conical section is connected to the tool head.

[0011] The aforementioned large-size ultrasonic plastic welding system is characterized in that: the metal front cover plate and the metal rear cover plate are both cylindrical bodies with equal cross-sections, each with a radius of 25mm and a height of 56mm, and both are made of aluminum 6063-T83; the piezoelectric ceramic crystal stack is a circular ring with equal cross-sections, an inner diameter of 25mm and a height of 6mm, and is made of PZT-4; the metal cylindrical section is a cylindrical body with equal cross-sections, a radius of 25mm and a height of 77mm, and is made of aluminum 6063-T83; the metal conical section is a cone with a base radius of 25mm, a top radius of 20mm, and a height of 45mm, and is made of aluminum 6063-T83.

[0012] The above-mentioned large-size ultrasonic plastic welding system is characterized in that the tool head 3 is made of aluminum, and the number of periodic fan-shaped cylindrical holes (m rows × n columns) satisfies: 2≤m≤12, 3≤n≤15, and the inner cylinder radius r1, outer cylinder radius r2, number of fan-shaped central angles s, and fan-shaped angle θ of the periodic fan-shaped cylindrical holes satisfy: 0.1mm≤r1≤10mm, 0.2mm≤r2≤16mm, 2≤s≤10, 1°≤θ≤36°.

[0013] The above-mentioned large-size ultrasonic plastic welding system is characterized in that the number of periodic sector-shaped cylindrical holes is 4 rows × 6 columns, and the inner cylinder radius r1 = 0.4 mm, the outer cylinder radius r2 = 2 mm, the number of central angles of the sector s = 4, and the sector angle θ = 3°.

[0014] The aforementioned large-size ultrasonic plastic welding system is characterized in that the surface grooves in the acoustic surface structure are elongated structures, respectively penetrating the XY plane, XZ plane, and YZ plane, and the number of surface grooves m1, n1, and q1 on the XY plane, XZ plane, and YZ plane satisfies: 2≤m1≤15, 2≤n1≤12, 2≤q1≤10, and the thickness h of the surface grooves is... w Width k w All satisfy: 0.1mm≤h w ≤10mm, 0.5mm≤k w ≤15mm.

[0015] The aforementioned large-size ultrasonic plastic welding system is characterized in that the number of grooves on the upper surfaces of the XY plane, XZ plane, and YZ plane is m1=8, n1=6, and q1=4, respectively, and the thickness of the surface grooves is h. w =0.2mm, width k w =3mm.

[0016] The aforementioned large-size ultrasonic plastic welding system is characterized in that the air grooves in the topological defect structure include normal air grooves and heterogeneous air grooves, both of which are cuboid structures. The number of normal air grooves m2 and heterogeneous air grooves m3 on the XZ plane, and the number of normal air grooves n2 and heterogeneous air grooves n3 on the YZ plane satisfy: 2≤m2≤10, 1≤m3≤5, 2≤n2≤8, 1≤n3≤4. The width w1 and height h1 of the normal air grooves and the width w1 and height h2 of the heterogeneous air grooves satisfy: 1mm≤w1≤10mm, 10mm≤h1≤80mm, 12mm≤h2≤100mm.

[0017] The above-mentioned large-size ultrasonic plastic welding system is characterized in that the number of normal air grooves m2=3 and the number of heterogeneous air grooves m3=1 on the XZ plane, the number of normal air grooves n2=3 and the number of heterogeneous air grooves n3=0 on the YZ plane, the width of the normal air grooves w1=6mm and the height h1=66mm, and the width of the heterogeneous air grooves w1=6mm and the height h2=81mm.

[0018] Compared with the prior art, the present invention has the following advantages: 1. The large-size ultrasonic plastic welding system of the present invention constructs an acoustic surface structure with high energy transmission efficiency by opening surface grooves on the XY plane, XZ plane and YZ plane of the tool head, which greatly improves the displacement amplitude of the welding system's radiation surface and improves the welding efficiency of the welding system.

[0019] 2. The large-size ultrasonic plastic welding system of the present invention constructs a near-periodic phonon crystal structure with a wide bandwidth by opening m rows × n columns of periodic fan-shaped cylindrical holes parallel to the Z axis on the XY plane of the tool head, thereby suppressing harmful transverse vibrations, improving the uniformity of amplitude distribution on the system's radiation surface, and enhancing the working accuracy of the welding system.

[0020] 3. The large-size ultrasonic plastic welding system of the present invention constructs a topological defect structure by opening through-hole air grooves in the XZ and YZ planes of the tool head, which effectively captures sound waves and increases the radiated sound power of the welding system, thereby increasing the displacement amplitude of the radiating surface of the welding system. At the same time, by adjusting the distribution of the mode field and vibration mode through the topological defect structure, the displacement distribution of the system's radiating surface becomes more uniform, thereby achieving the purpose of improving the uniformity of the displacement amplitude distribution of the radiating surface of the large-size ultrasonic plastic welding system and improving the welding accuracy.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the large-size ultrasonic plastic welding system of the present invention.

[0023] Figure 2 This is a front view of the large-size ultrasonic plastic welding system of the present invention.

[0024] Figure 3 This is a schematic diagram of the periodic fan-shaped cylindrical hole and surface groove structure of the tool head in the XY plane of the large-size ultrasonic plastic welding system of the present invention.

[0025] Figure 4 for Figure 3 A schematic diagram of the cross-section of a periodic sector-shaped cylindrical hole.

[0026] Figure 5 This is a schematic diagram of the surface groove and air groove structure of the tool head XZ plane of the large-size ultrasonic plastic welding system of the present invention.

[0027] Figure 6 This is a schematic diagram of the surface groove and air groove structure of the tool head YZ plane of the large-size ultrasonic plastic welding system of the present invention.

[0028] Figure 7 This is a comparison diagram of the radiation surface displacement distribution between the large-size ultrasonic plastic welding system of the present invention and the unoptimized large-size ultrasonic plastic welding system.

[0029] Figure 8 This is a mode shape diagram of the large-size ultrasonic plastic welding system of the present invention.

[0030] Figure 9 The vibration mode diagram of an unoptimized large-size ultrasonic plastic welding system.

[0031] Explanation of reference numerals in the attached figures Detailed Implementation

[0032] Example 1 like Figure 1 and Figure 2 As shown, the large-size ultrasonic plastic welding system in this embodiment is composed of an ultrasonic transducer 1, a composite amplitude transformer 2, and a tool head 3 connected in sequence. The ultrasonic transducer 1 is composed of a metal front cover plate 4, a piezoelectric ceramic crystal stack 5, and a metal rear cover plate 6 connected in sequence. The composite amplitude transformer 2 is composed of a metal conical section 7 and a metal cylindrical section 8 connected in sequence. The tool head 3 is a metal cuboid. The metal cuboid has m rows × n columns of periodic fan-shaped cylindrical holes 9 parallel to the Z-axis on its XY plane. Surface grooves 10 are formed on the XY plane, XZ plane, and YZ plane, forming an acoustic surface structure. Through air grooves are formed on the XZ plane and YZ plane, forming a topological defect structure.

[0033] Typically, the ultrasonic transducer 1, the composite amplitude transformer 2, and the tool head 3 are connected by bolts; the metal front cover plate 4, the piezoelectric ceramic crystal stack 5, and the metal rear cover plate 6 are connected by bolts; and the metal conical section 7 and the metal cylindrical section 8 are connected by bolts. By adopting a simple and easy-to-operate bolt connection method, a tight connection between the various components of the large-size ultrasonic plastic welding system is achieved, which is easy to assemble and disassemble, facilitating system maintenance and replacement.

[0034] Previous studies have found that large-size ultrasonic plastic welding systems experience severe lateral vibrations due to the Poisson effect. The coupling of longitudinal and lateral vibrations leads to uneven amplitude distribution on the welding system's radiating surface, preventing the uniform transfer of vibration energy to the workpiece surface. In severe cases, this can even cause localized overflow or incomplete welding, affecting weld quality. Furthermore, due to the large size of the ultrasonic plastic welding system, the coupled vibrations inevitably result in increased energy loss and smaller displacement of the radiating surface, significantly impacting the system's efficiency. To address this, the large-size ultrasonic plastic welding system in this embodiment controls lateral vibrations to improve the uniformity of displacement distribution on the welding surface, promoting the engineering application of large-size ultrasonic plastic welding systems.

[0035] Specifically, in the large-size ultrasonic plastic welding system of this embodiment, an ultrasonic transducer 1 is formed by sequentially connecting a metal front cover plate 4, a piezoelectric ceramic crystal stack 5, and a metal rear cover plate 6 to convert high-frequency electrical energy into high-frequency longitudinal vibration through the piezoelectric effect. A composite amplitude transformer 2 is formed by connecting a metal conical segment 7 and a metal cylindrical segment 8 to amplify the vibration amplitude, improve energy transfer efficiency, and perform impedance matching. Based on this, the tool head 3 is structurally designed by creating m rows × n columns of periodic fan-shaped cylindrical holes 9 parallel to the Z-axis on the XY plane of the metal cuboid of the tool head 3 to construct a near-period phonon crystal structure with a wide bandwidth. This structure can significantly increase the band gap, achieve better suppression of harmful transverse vibrations, make the vibration modes more uniform, effectively improve the uniformity of amplitude distribution on the system's radiation surface, and improve the working accuracy of the welding system. In this embodiment, surface grooves 10 are respectively opened on the XY plane, XZ plane, and YZ plane of the metal cuboid to form an acoustic surface structure, constructing an acoustic surface structure with high energy transmission efficiency, realizing acoustic collimation and acoustic anomalous transmission phenomena, exciting a strong localization effect of sound waves, greatly increasing the displacement amplitude of the welding system's radiation surface, further improving the transmission efficiency of ultrasonic energy, thereby improving the welding efficiency of the welding system. This embodiment creates a topological defect structure by opening through-hole air grooves in the XZ and YZ planes of the metal cuboid, which traps sound waves at the defect dispersion point. This effectively improves the problem of increased energy loss caused by coupled vibration, significantly increases the radiated sound power and energy transmission efficiency of the welding system, thereby increasing the displacement amplitude of the radiating surface of the welding system and improving its welding efficiency.

[0036] like Figure 1 and Figure 2 As shown, the metal front cover plate 4 and the metal rear cover plate 6 are both cylinders, and the front end face of the piezoelectric ceramic crystal stack 5 is connected to the rear end face of the metal rear cover plate 6, and the rear end face is connected to the front end face of the metal front cover plate 4.

[0037] like Figure 1 and Figure 2 As shown, the metal cylindrical segment 8 is further connected to the rear end face of the metal front cover plate 4, and the metal conical segment 7 is connected to the tool head 3.

[0038] Furthermore, the metal front cover plate 4 and the metal rear cover plate 6 are both cylinders with equal cross-sections, each with a radius of 25mm and a height of 56mm, and are both made of aluminum 6063-T83; the piezoelectric ceramic crystal stack 5 is a ring with equal cross-sections, an inner diameter of 25mm and a height of 6mm, and is made of PZT-4; the metal cylindrical segment 8 is a cylinder with equal cross-sections, a radius of 25mm and a height of 77mm, and is made of aluminum 6063-T83; the metal conical segment 7 is a cone with a base radius of 25mm, a top radius of 20mm, and a height of 45mm, and is made of aluminum 6063-T83.

[0039] like Figure 3 and Figure 4As shown, further, the tool head 3 is made of aluminum, and the number of periodic sector-shaped cylindrical holes 9, m rows × n columns, satisfies: 2≤m≤12, 3≤n≤15, and the inner cylinder radius r1, outer cylinder radius r2, number of sector central angles s, and sector angle θ of the periodic sector-shaped cylindrical holes 9 satisfy: 0.1mm≤r1≤10mm, 0.2mm≤r2≤16mm, 2≤s≤10, 1°≤θ≤36°. This invention has found that the number of periodic sector-shaped cylindrical holes 9 is limited by the tool head size. Too many holes not only make processing difficult but also lead to uneven distribution of displacement amplitude in the welding system, poor suppression of lateral vibration, and a small average displacement amplitude. Conversely, too few holes, while easier to process, also lead to uneven distribution of displacement amplitude in the welding system, poor suppression of lateral vibration, and a small average displacement amplitude. Therefore, by limiting the quantities of m, n, and s, the uniformity of the amplitude distribution on the system's radiation surface and the suppression effect of the near-periodic phonon crystal structure on harmful lateral vibrations are ensured. More preferably, m is 4, n is 6, and s is 4. Furthermore, the influence of the inner cylinder radius r1, the outer cylinder radius r2, and the sector angle θ on the frequency, radiation surface displacement amplitude, and amplitude distribution of the welding system is further analyzed. It is concluded that when r1 is in the range of 0.3mm~0.4mm or 1.2mm~1.5mm, r2 is in the range of 2mm~4mm, and θ is 3° or in the range of 8°~10°, the uniformity of the radiation surface amplitude distribution and the displacement amplitude of the welding system can reach the most ideal state.

[0040] Furthermore, the number of periodic sector-shaped cylindrical holes 9 is 4 rows × 6 columns, and the inner cylinder radius r1 = 0.4 mm, the outer cylinder radius r2 = 2 mm, the number of central angles of the sector s = 4, and the sector angle θ = 3°.

[0041] like Figure 1 and Figure 2 As shown, further, the surface grooves in the acoustic surface structure are elongated structures, respectively penetrating the XY plane, XZ plane, and YZ plane, and the number m1, n1, and q1 of surface grooves 10 on the XY plane, XZ plane, and YZ plane satisfy: 2≤m1≤15, 2≤n1≤12, 2≤q1≤10, and the thickness h of the surface grooves 10 is... w Width k w All satisfy: 0.1mm≤h w ≤10mm, 0.5mm≤k w≤15mm. Typically, the surface grooves in the XY plane are interlaced horizontally and vertically, while the surface grooves in the XZ and YZ planes are longitudinal grooves parallel to the air grooves. By limiting the number, size, and distribution of surface grooves on each plane, the tool head size requirements are met. This avoids problems such as excessive quantity leading to processing difficulties, uneven distribution of welding system displacement amplitude, poor suppression of lateral vibration, and small average displacement amplitude. Conversely, while excessive quantity may facilitate processing, it can also lead to uneven distribution of welding system displacement amplitude, poor suppression of lateral vibration, and small average displacement amplitude. This ensures that the acoustic surface structure significantly improves the displacement amplitude of the welding system's radiating surface, thereby increasing the welding efficiency of the welding system.

[0042] Furthermore, the number of grooves 10 on the upper surfaces of the XY plane, XZ plane, and YZ plane is m1=8, n1=6, and q1=4, respectively, and the thickness of the surface grooves 10 is h. w =0.2mm, width k w =3mm.

[0043] like Figure 5 and Figure 6 As shown, further, the air slots in the topological defect structure include normal air slots 11 and heterogeneous air slots 12, both of which are cuboid structures. The number of normal air slots 11 m2 and heterogeneous air slots 12 m3 on the XZ plane, and the number of normal air slots 11 n2 and heterogeneous air slots 12 n3 on the YZ plane satisfy: 2≤m2≤10, 1≤m3≤5, 2≤n2≤8, 1≤n3≤4. The width w1 and height h1 of the normal air slots 11 and the width w1 and height h2 of the heterogeneous air slots 12 satisfy: 1mm≤w1≤10mm, 10mm≤h1≤80mm, 12mm≤h2≤100mm. This invention has discovered that by designing the air channels as a normal air channel 11 and a heterogeneous air channel 12, with the heterogeneous air channel 12 being slightly higher than the normal air channel 11 to create a defect, the two types of air channels achieve in-phase resonance between the normal scattering element and the defective scattering element. This results in comparable local mode field amplitudes and identical phases, leading to a more uniform displacement distribution on the radiation surface of the welding system. This improves the uniformity of the displacement amplitude distribution on the radiation surface of large-size ultrasonic plastic welding systems, thereby enhancing welding accuracy. Typically, the normal air channel 11 and the heterogeneous air channel 12 appear in pairs; the heterogeneous air channel 12 appears in pairs, in even numbers, and in symmetrical positions to ensure the performance of the welding system.

[0044] Furthermore, the number of normal air slots 11 on the XZ plane is m2=3, the number of heterogeneous air slots 12 is m3=1, the number of normal air slots 11 on the YZ plane is n2=3, the number of heterogeneous air slots 12 is n3=0, the width of the normal air slot 11 is w1=6mm, the height is h1=66mm, and the width of the heterogeneous air slot 12 is w1=6mm and the height is h2=81mm.

[0045] The large-size ultrasonic plastic welding system of this embodiment was tested and compared with the unoptimized large-size ultrasonic plastic welding system, and the results are as follows: Figures 7-9 As shown in Table 1, compared to the large-size ultrasonic plastic welding system (optimized system) of this embodiment, the tool head of the unoptimized large-size ultrasonic plastic welding system (unoptimized system) is a conventional metal cuboid structure. No improvements or optimizations have been made to its structure. Therefore, the displacement amplitude output from its radiation surface is small. The amplitude is too small to reach the required amplitude, making it difficult for the workpiece to melt, resulting in insufficient welding. At the same time, the uniformity of the amplitude distribution output from its welding surface is extremely poor. This will cause the vibration energy of the welding surface to be unevenly transmitted, resulting in local overflow or missed welding of the workpiece, which affects the quality of ultrasonic plastic welding.

[0046] Table 1

[0047] Combination Figures 7-9 As shown in Table 1, the radiating surface displacement amplitude of the large-size ultrasonic plastic welding system in this embodiment is 8.505 times that of the unoptimized large-size ultrasonic plastic welding system. The increase in displacement amplitude means a reduction in welding time and an increase in welding efficiency. At the same time, the uniformity of the radiating surface amplitude distribution of the large-size ultrasonic plastic welding system in this embodiment is 2004.660 times that of the unoptimized large-size ultrasonic plastic welding system. This means that the optimized system can ensure efficient and stable transmission and output of amplitude and energy, and can meet the requirements of high efficiency and reliability in welding processing. This indicates that by improving the tool head structure of the large-size ultrasonic plastic welding system, this embodiment effectively improves the adverse effects of coupled vibration by using periodic fan-shaped cylindrical holes, acoustic surface structures, and topological defect structures. By increasing the displacement amplitude and improving its distribution uniformity, the welding efficiency and working accuracy are effectively improved.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A large-size ultrasonic plastic welding system, characterized in that, The device is composed of an ultrasonic transducer (1), a composite amplitude transformer (2), and a tool head (3) connected in sequence. The ultrasonic transducer (1) is composed of a metal front cover plate (4), a piezoelectric ceramic crystal stack (5), and a metal rear cover plate (6) connected in sequence. The composite amplitude transformer (2) is composed of a metal conical section (7) and a metal cylindrical section (8) connected in sequence. The tool head (3) is a metal cuboid. The metal cuboid has m rows × n columns of periodic fan-shaped cylindrical holes (9) parallel to the Z axis on the XY plane. The XY plane, XZ plane, and YZ plane are respectively provided with surface grooves (10) to form an acoustic surface structure. The XZ plane and YZ plane are respectively provided with through air grooves to form a topological defect structure.

2. The large-size ultrasonic plastic welding system according to claim 1, characterized in that, Both the metal front cover plate (4) and the metal rear cover plate (6) are cylindrical, and the front end face of the piezoelectric ceramic crystal stack (5) is connected to the rear end face of the metal rear cover plate (6), and the rear end face is connected to the front end face of the metal front cover plate (4).

3. The large-size ultrasonic plastic welding system according to claim 1, characterized in that, The cylindrical metal section (8) is connected to the rear end face of the metal front cover plate (4), and the conical metal section (7) is connected to the tool head (3).

4. The large-size ultrasonic plastic welding system according to claim 1, characterized in that, The metal front cover plate (4) and the metal rear cover plate (6) are both cylindrical bodies with equal cross-sections, each with a radius of 25 mm and a height of 56 mm, and are made of aluminum 6063-T83. The piezoelectric ceramic crystal stack (5) is a circular ring with equal cross-sections, an inner diameter of 25 mm and a height of 6 mm, and is made of PZT-4. The metal cylindrical section (8) is a cylindrical body with equal cross-sections, a radius of 25 mm and a height of 77 mm, and is made of aluminum 6063-T83. The metal conical section (7) is a cone with a bottom radius of 25 mm, a top radius of 20 mm and a height of 45 mm, and is made of aluminum 6063-T83.

5. A large-size ultrasonic plastic welding system according to claim 1, characterized in that, The tool head (3) is made of aluminum. The number of periodic sector-shaped cylindrical holes (9) is m rows × n columns, which satisfies: 2≤m≤12, 3≤n≤15. The inner cylinder radius r1, outer cylinder radius r2, number of sector central angles s, and sector angle θ of the periodic sector-shaped cylindrical holes (9) satisfy: 0.1mm≤r1≤10mm, 0.2mm≤r2≤16mm, 2≤s≤10, 1°≤θ≤36°.

6. A large-size ultrasonic plastic welding system according to claim 1, characterized in that, The number of periodic sector-shaped cylindrical holes (9) is 4 rows × 6 columns, and the inner cylinder radius r1 = 0.4 mm, the outer cylinder radius r2 = 2 mm, the number of central angles s = 4, and the sector angle θ = 3° of the periodic sector-shaped cylindrical holes (9) are 4.

7. A large-size ultrasonic plastic welding system according to claim 1, characterized in that, The surface grooves in the acoustic surface structure are elongated structures, and they penetrate the XY plane, XZ plane, and YZ plane respectively. The number m1, n1, and q1 of the surface grooves (10) on the XY plane, XZ plane, and YZ plane satisfy: 2≤m1≤15, 2≤n1≤12, 2≤q1≤10, and the thickness h of the surface grooves (10) is... w Width k w All satisfy: 0.1mm≤h w ≤10mm, 0.5mm≤k w ≤15mm.

8. A large-size ultrasonic plastic welding system according to claim 1, characterized in that, The number of grooves (10) on the upper surfaces of the XY plane, XZ plane, and YZ plane are m1=8, n1=6, and q1=4, respectively, and the thickness of the grooves (10) is h. w =0.2mm, width k w =3mm.

9. A large-size ultrasonic plastic welding system according to claim 1, characterized in that, The air slots in the topological defect structure include normal air slots (11) and heterogeneous air slots (12), both of which are cuboid structures. The number of normal air slots (11) m2 and heterogeneous air slots (12) m3 on the XZ plane, and the number of normal air slots (11) n2 and heterogeneous air slots (12) n3 on the YZ plane satisfy: 2≤m2≤10, 1≤m3≤5, 2≤n2≤8, 1≤n3≤4. The width w1 and height h1 of the normal air slots (11) and the width w1 and height h2 of the heterogeneous air slots (12) satisfy: 1mm≤w1≤10mm, 10mm≤h1≤80mm, 12mm≤h2≤100mm.

10. A large-size ultrasonic plastic welding system according to claim 1, characterized in that, The number of normal air slots (11) on the XZ plane is m2=3, the number of heterogeneous air slots (12) is m3=1, the number of normal air slots (11) on the YZ plane is n2=3, the number of heterogeneous air slots (12) is n3=0, the width of the normal air slot (11) is w1=6mm, the height is h1=66mm, the width of the heterogeneous air slot (12) is w1=6mm, and the height is h2=81mm.

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