Design and Experimental Research for the Ultrasonic Burnishing System on Rods for Hydraulic Applications Surfaces

To explore the effects of ultrasonic burnishing strengthening technology on the surface morphology and mechanical properties of 40Cr rods for hydraulic applications, a conical transition composite amplitude transformer was designed using ANSYS (Workbench 2024 R1) finite element analysis software, with a frequency of 18,158 Hz, an amplification factor (<i>M_p</i>) of 2.0, and a maximum stress of 122.9 MPa. The ultrasonic burnishing strengthening process was numerically simulated via ABAQUS finite element analysis software. Based on the single-factor analysis method, the influence of spindle speed, ultrasonic amplitude, and burnishing passes on the maximum residual compressive stress of the hydraulic rod was investigated, and key parameters such as surface roughness and microhardness of the rod before and after ultrasonic burnishing strengthening were comparatively analyzed. The results show that ultrasonic burnishing strengthening technology can reduce the surface roughness of the hydraulic rod, enhance its microhardness, and increase the depth of the plastic deformation layer. Ultrasonic amplitude and burnishing passes exert a significant influence on the maximum residual compressive stress on the rod surface, while the effect of spindle speed is relatively minor. When the ultrasonic amplitude is 10 μm, the spindle speed is 120 r/min, and the burnishing passes are 3, the surface residual compressive stress of the hydraulic rod reaches the maximum experimental value of 433.39 MPa. This study reveals the influence law of process parameters on the surface properties of rods for hydraulic applications, verifies the feasibility of the ultrasonic burnishing system, and provides a technical reference for improving the performance of rods for hydraulic applications.