Application Cases

Experiment Name: Application of Power Amplifier in Research on Ultrasonic-Assisted Polyurethane Blanking Process

Research Direction:
The polyurethane blanking process is a process in which a polyurethane elastic pad is used to interact with a metal mold to perform punching or cutting actions on sheet materials, thereby obtaining punched or blanked parts. A polyurethane micro-hole array blanking mold was designed. Ultrasonic vibration with a frequency of 40 kHz was applied to the punch for blanking experiments, and the experimental results were analyzed. By selecting an ultrasonic power supply, designing an ultrasonic transducer, analytically designing a conical horn based on the dimensions of the transducer and punch, and optimizing the horn structure using ANSYS, ultrasonic-assisted polyurethane micro-hole array blanking experiments were conducted. The results show that the softening effect of ultrasonic vibration optimizes the blanking process, expands the process parameter range of the mold, and reduces the influence of die hole depth on the sheet forming process, thereby achieving a reduction in mold processing costs.

Test Objective:
Ultrasonic-assisted polyurethane micro-hole array blanking experiments were conducted to investigate the optimization effect of ultrasonic vibration on the blanking process.

Testing Equipment:
ATA-4052 high-voltage power amplifier, signal generator.

Experimental Content:
Micro-blanking refers to a blanking process where the dimensions of the blanked part are on the submillimeter scale in both directions. This process can induce size effects in materials and requires high mold alignment accuracy. Researchers have extensively studied how to ensure the dimensional and shape accuracy of micro-blanked parts. Mold processing in micro-blanking presents technical difficulties. Common processing methods include laser milling and micro-electrical discharge machining (EDM). However, these methods suffer from problems such as high cost and long processing cycles. Polyurethane blanking is a typical flexible die stamping technology. It uses a highly elastic polyurethane pad as a flexible die to replace the male and female dies in traditional rigid die sets. The polyurethane elastic pad is combined with the metal mold to achieve blanking. The earliest flexible die stamping technology originated in the late 19th century. This technology can solve scratching problems during blanking to some extent. Since then, flexible die stamping technology has gradually matured and has been widely used in industrial production and other fields. The most famous example is the aircraft panel manufactured using the Greene rubber pad forming method. This demonstrates that the technology can be used to produce high-precision parts with few defects. Although flexible die stamping and micro-blanking technologies have mature mechanistic research and applications, some problems still exist, such as: ① High alignment accuracy required for male and female dies, making alignment difficult; ② The polyurethane punching method lacks mechanical simulations that can solidify the theoretical foundation; ③ Polyurethane punching has high requirements for the depth of the die hole, often resulting in excessively large punched hole rollover zones. To address these problems, this paper mainly studies the following: ① A polyurethane micro-hole array blanking device was designed and built, and single-factor blanking experiments were conducted; ② The variation patterns of punched hole diameter and cross-section quality with sheet thickness, die hole depth, blanking force, and blanking speed were investigated; ③ A horn was designed using analytical methods, finite element optimization was performed, and ultrasonic-assisted polyurethane micro-hole array blanking experiments were conducted to explore the optimization effect of ultrasonic vibration on the blanking process.

Test System:
The experiment used a signal generator and an ATA-4052 power amplifier to form the ultrasonic power supply in the ultrasonic module. This setup was used to enhance the high-frequency oscillation signal with a fixed frequency. This signal generator is a versatile dual-channel function/arbitrary waveform generator. It can output sinusoidal waveforms with frequencies up to 60 MHz and a sampling rate of 500 MSa/s. However, it has the problem of low maximum output signal amplitude, which cannot meet the amplitude required for processing. Therefore, it was paired with the ATA-4052 power amplifier to amplify its amplitude. The combined action of the two maintained a stable output of ultrasonic vibration amplitude.

Experimental Results:
(1) A polyurethane micro-hole array blanking device was designed. An ultrasonic-assisted module was designed and assembled, and research was conducted on the optimization of the polyurethane blanking process using ultrasonic vibration. A special process was proposed for the first time, in which rigid die blanking and flexible die punching are sequentially completed within one stamping stroke. Single-factor experiments investigated the influence of die hole depth, blanking force, and blanking speed on the blanking process and workpiece quality. The optimization effect of ultrasonic vibration on the process and its role in improving blanked part quality were verified.

(2) By designing and assembling the ultrasonic module and measuring the amplitude, it was found that the amplitude increased with the input amplitude of the power supply signal. Ultrasonic-assisted polyurethane micro-hole array blanking experiments showed that die holes with depths of 200, 300, and 400 μm could all be successfully punched, producing blanked parts with micro-hole arrays. The power supply signal amplitude was adjusted for ultrasonic-assisted blanking experiments, and the cross-sections of the punched holes were observed. The results showed that ultrasonic vibration improved the cross-sectional morphology of the punched holes. As the amplitude increased, the proportion of the shear bright band in the punched hole cross-section increased from 57% (without ultrasonic vibration) to 81%, significantly improving the cross-section quality.

Figure: Specifications of the ATA-4052C High-Voltage Power Amplifier