Design and Research of a New Type of Ultrasonic Vibration De-Gluing Device

In this paper, a new type of ultrasonic vibration de-gluing device has been designed to remove the cured epoxy resin adhesive that overflowed from the aluminum alloy structural parts in the high-speed train carriages. At present, manual removal is used to remove the cured epoxy resin adhesive that over-flows at the bonding site. This method has low removal efficiency and leads to poor surface quality of the parts. The new type of ultrasonic vibration de-gluing device can solve these problems. Modal analysis and harmonic response analysis are carried out on the ultrasonic vibration oscillator system in the ultrasonic vibration de-gluing device, and the reasonable structure parameters and resonance frequency of the ultrasonic vibration oscillator system are determined. Finally, the impedance test and de-gluing effect test are carried out on the prototype of the ultrasonic vibration de-gluing device to verify the feasibility and practicability of the new type of ultrasonic vibration de-gluing device. The results show that the ultrasonic vibration de-gluing device’s stable resonant operating frequency is 28,270 Hz, and the average error between the simulation and experimental results of the resonant operating frequency is less than 3%, which validates the simulation model.


Introduction
Some of the aluminum alloy structures in the high-speed train carriages need to be bonded with epoxy resin adhesive. However, the excess epoxy resin adhesive will overflow and solidify at the bonding edge, which greatly affects the appearance of the structures and leads to the inaccurate assembly of the aluminum al-World Journal of Engineering and Technology loy structures. At present, manual removal is used to remove the cured epoxy resin adhesive that overflowed from the bonding. This method not only consumes a lot of labor, but also has low removal efficiency [1]. In addition, the surface quality of the aluminum alloy structures removed manually is poor.
Laser cleaning technology is an industrial technology to remove epoxy resin adhesive [2]. This technology utilizes the interaction between laser and material.
It has the characteristics of high machining precision and no contact with the processed object, so that epoxy resin adhesive can be selectively removed. At present, laser cleaning technology is mostly used for the removal of epoxy coatings on aerospace equipment, and the equipment cost is relatively high. However, the thickness of epoxy resin adhesive removal is usually below 0.1 mm, which is much lower than the thickness of cured epoxy resin adhesive overflowing from aluminum alloy structural parts in high-speed train carriages. In addition, epoxy resin laser cleaning will generate harmful gas, which is not friendly to the environment.
A set of ultrasonic vibration de-gluing devices was developed to remove the cured epoxy resin adhesive that overflowed from the aluminum alloy structural parts after bonding. In order to design and optimize the structure of the ultrasonic vibration oscillator system, finite element analysis was carried out on the ultrasonic vibration oscillator system in the ultrasonic vibration de-gluing device. The impedance test and de-gluing test were carried out on the prototype of the ultrasonic vibration de-gluing device. The feasibility and practicability of the new type of ultrasonic vibration de-gluing device are verified. Compared with the traditional manual removal and laser cleaning technology, the ultrasonic vibration de-gluing device can achieve a balance of processing speed and precision, thus improving the removal efficiency and quality.

Overall Structure and Working Principle of the Ultrasonic
Vibration De-Gluing Device Figure 1 shows the structure sketch of the new type of ultrasonic vibration de-gluing device. The device mainly consists of ultrasonic transducer, amplitude transformer, the cutter head, device housing and handle. The ultrasonic transducer, amplitude transformer and the cutter head are assembled into the ultrasonic vibration oscillator system. The ultrasonic vibration transducer is connected to the rear of the amplitude transformer through a stud, the cutter head is connected to the front of the amplitude transformer through a stud, and the amplitude transformer is connected to the device housing through a flange. The amplitude transformer is a stepped structure with an arc transition [3]; the cutter head is also designed as a stepped structure. The connecting section between the cutter head and the amplitude transformer is a cylindrical section, and the front of the cutter head is a flat edge structure. This structure can also amplify the amplitude, which is conducive to amplifying the amplitude at the end of the cutter head. The handle is connected to the device shell. The ultrasonic power supply is connected to the electrodes of the ultrasonic transducer through wires. When the transducer receives the alternating signal from the ultrasonic power supply, it will generate axial high-frequency vibration. The amplitude transformer amplifies the vibration amplitude and transmits it to the cutter head, driving it to vibrate at high frequency [4]. When the cutter head comes into contact with the overflowing epoxy resin adhesive, the cured epoxy resin adhesive will be broken into powder by high-frequency vibration, which can be easily removed.
In order to verify the feasibility of such structure theoretically, a finite element analysis of the device model is required.

Finite Element Analysis of the Ultrasonic Vibration
Oscillator System in the Ultrasonic Vibration De-Gluing Device

Model Analysis of the Ultrasonic Vibration Oscillator System
After the preliminary design of ultrasonic vibration de-gluing device is completed, the modal analysis of the ultrasonic vibration oscillator system in the ultrasonic vibration de-gluing device is carried out using ANSYS Workbench. The natural frequency and vibration model of the ultrasonic vibration oscillator system can be determined through modal analysis. The materials of the parts in the ultrasonic vibration oscillator system materials are defined separately. The anisotropic elastic parameter matrix of PZT-8 is added to the material library, and its density is defined as 7500 kg/m 3 . The fastening studs in the ultrasonic transducer are defined as 45 steel, the four piezoelectric ceramic plates are defined as PZT-8, the four electrode plates are defined as brass, the rear cover plate of the ultrasonic transducer and the amplitude transformer are defined as 304 stainless steel, the front cover plate of the ultrasonic transducer is defined as hard aluminum 2021, the connecting bolts between the amplitude transformer and the cutter head are defined as 45 steel, and the cutter head is defined as titanium alloy TC4 [5]. The mesh element size is set to 1.5 mm, the frequency solution range is 0 -30,000 hz, the solution result is set as total deformation, and the limitation of modal solutions is set up to 100. Finally, 50 modes are found, and 3 longitudinal vibration modes are extracted. The natural frequency of the oscillator system is shown in Table 1.
The third-class modal shape diagram of the ultrasonic vibration oscillator system is shown in Figure 2. It illustrates that the node with the largest amplitude is World Journal of Engineering and Technology     axially in the Y direction in this modality. In addition, the oscillator system can obtain a large amplitude ratio, which can reach 24. It shows that the structure can effectively amplify the amplitude from the ultrasonic transducer.

Harmonic Response Analysis of the Ultrasonic Vibration Oscillator System
To determine the steady-state response of the ultrasonic vibration oscillator system electrified by voltage signal, it is necessary to perform harmonic response analysis based on the modal analysis of the ultrasonic vibration oscillator system. World Journal of Engineering and Technology There are multiple methods for the harmonic response analysis of the ultrasonic vibration oscillator system. In the current work, a simple and adaptable approach that combines the commands and the MEMS ACT plug-in is used.
The analysis type is set as harmonic response analysis, and the calculate method is set as full method. By installing MEMS ACT plug-in, the four PZT-8 piezoe- The frequency response post processor in the Workbench is used to obtain the variation curve of the amplitude of the node at the output end of the ultrasonic vibration oscillator system with the frequency, as shown in Figure 6. When the frequency reaches 28,700 hz, the amplitude of the node reaches the peak value,

Impedance Test Experiment of Ultrasonic Vibration Glue Removal Device
Since the finite element analysis has fully validated the theoretical feasibility of the ultrasonic vibration oscillator system in the ultrasonic vibration de-gluing device, the prototype of the ultrasonic vibration de-gluing device was manufactured for experiments, which can verify its practical feasibility.
The impedance test experiment is used to measure the impedance parameters of the ultrasonic vibration de-gluing device in the ultrasonic vibration de-gluing device, to provide a basis for the impedance matching between the ultrasonic vibration de-gluing device and the ultrasonic power supply. The admittance circle ( Figure 9) and impedance curve (Figure 10) of the ultrasonic vibration de-gluing device are measured by the "pv90a" impedance analyzer. The measured impedance data of the ultrasonic vibration de-gluing device is very close to the finite element analysis results, and the error is less than 4.5%. It is verified that the World Journal of Engineering and Technology     The epoxy resin adhesive in Figure 11 is removed along the side of the aluminum alloy, and the red part is the processed surface.

Test of the Ultrasonic Vibration De-Gluing Device
As shown in Figure 12, an epoxy resin adhesive de-gluing platform has been built, and an ultrasonic power supply with a rated frequency of 28,000 Hz is used to power the ultrasonic vibration de-gluing device. The rated power of the power supply is 800 W, the default output frequency is 28,000 Hz, and the frequency can be tracked within the range of ±5000 Hz.
The ultrasonic power supply generates a sinusoidal voltage power with a peak voltage of 1400 V to the ultrasonic vibration de-gluing device, so that the ultra-  The experimental sample is a 700 mm × 120 mm × 32 mm hollow aluminum alloy structural part, the overflow area of the cured epoxy resin adhesive to be processed is 25 mm × 80 mm, and the thickness of the epoxy resin adhesive is 2.5 mm. The ultrasonic vibration de-gluing device is used to remove the cured epoxy resin adhesive in this area. After 30 s of de-gluing operation, the appearance comparison of the samples before and after de-gluing is shown in Figure   13. The 2.5 mm thick cured epoxy resin adhesive is removed, and the processing surface is relatively smooth. For the manual removal method, it is almost impossible to remove the overflow cured epoxy resin adhesive when using 50N

Conclusions
In this article, a new type of ultrasonic vibration de-gluing device with a resonant frequency of 28,270 hz was developed to solve the problem of removing the overflowed and cured epoxy resin adhesive on the aluminum alloy structural parts in the high-speed train carriages.
Herein, the structure of the new ultrasonic vibration de-gluing device was de- The new type of ultrasonic vibration de-gluing device is used to remove 2.5 mm thick cured epoxy resin, and the de-gluing speed can reach 1.2 m 2 /h. It can be seen that the use of the ultrasonic vibration de-gluing device can not only greatly improve the de-gluing efficiency, but also improve the surface quality of de-gluing, which verifies the feasibility and practicability of the new ultrasonic vibration de-gluing device.
The ultrasonic vibration de-gluing device can remarkably increase the processing efficiency of the aluminum alloy structural parts in high-speed train carriages. In addition, it can save lots of labor and make the aluminum alloy structural parts beautiful and practical. In addition, it can also be applied to other vehicles other than high-speed trains, such as e de-gluing work of aluminum alloy structural parts in buses and light rail cars.