Abstract:In order to reveal the mechanism and advantages of ultrasonic technology in cutting and harvesting clustered tomatoes, the cutting force and removal characteristics of clustered tomato stem materials in conventional cutting and ultrasonic cutting were compared. Firstly, the parameters of clustered tomato fruit stalks and self-made ultrasonic cutting knife were measured, and then the fruit stalks were fiberized based on Abaqus simulation. The stress and removal mechanism during conventional cutting and ultrasonic cutting were compared in macro and micro simulation. Finally, the self-made test bench was used to measure the cutting force by changing the excitation frequency, input voltage, cutting speed and cutting angle of the ultrasonic cutting knife, and the Box-Behnken of response surface method was used to analyze the four factors and three levels, and then the crosssection morphology of the fruit stalk was observed. The results showed that within the working frequency (35~37kHz) and voltage (340~380V) of the self-made ultrasonic scalpel, the cutting speed and angle had the most significant influence on the cutting effect, and the cutting effect was the best when the excitation frequency and input voltage were near a specific value. Under the conditions of 36kHz, 360V, 0.125cm/s, and 0°, the ultrasonic cutting time in the simulation was about 8s, and the average maximum cutting force was 0.635N, which was 37.7% lower than that of the conventional cutting (1.019N). In the experiment, the ultrasonic cutting took about 5.3s, and the maximum cutting force required was 0.543N, which was 46.6% lower than that of the conventional maximum cutting force (1.017N), and the surface roughness was 20.9% lower. The error between the experimental and finite element simulation results was 8.9%, which was basically consistent. Ultrasonic cutting can reduce the cutting force, shorten the cutting time, improve the section quality, reduce the damage of fruit stem tissue and water loss, which was of certain significance to prolong the fruit preservation time.
