Research on the influence of ultrasonic on the inner rib’s surface morphology of ribbed cylindrical parts in flow spinning process

Abstract

• Ultrasonic-assisted flow spinning platform is established. • Ultrasonic reduces the deformation and friction resistance. • Application of ultrasonic benefits the material flow in spinning. • Rib tip surface morphology is more uniform with ultrasonic. • Quality of the inner longitudinal ribs is enhanced with ultrasonic. Thin-walled shell with inner ribs is the main load bearing structure for aerospace products, which decides the products overall performance. Flow spinning process is an effective method to realize the integrated manufacturing of thin-walled shells with inner ribs. However, this process still has defects of insufficient filling at the rib groove and fracture at the rib root. A novel process is proposed to fabricate the thin-walled shell with inner ribs by introducing ultrasonic energy into flow spinning process based on the softening effect and friction-reducing effect of the ultrasonic energy. This paper focuses on the forming quality of the inner longitudinal ribs. The longitudinal ribs are designed along the axial direction of the cylindrical parts. The rheological characteristics of material forming with ultrasonic is studied and the local cumulative deformation law of the inner rib material at the rib groove is revealed. The ultrasonic-assisted flow spinning platform was established and ultrasonic energy was introduced in the radial direction of the initial cylindrical parts. The experiment results with different ultrasonic amplitudes showed that the rib tip’s surface morphology and rib height were improved with ultrasonic. The finite element models were established to analyze the deformation characteristics of the inner ribs. The constitutive equation was established to reflect the material flowing property with ultrasonic. The simulation results showed that the material flowed into the groove more at the screw-in end and flowed out more at the screw-out end with ultrasonic. This flow state reduced the material accumulation phenomenon at the screw-out end. The tip’s surface morphology of inner longitudinal ribs were more uniform with ultrasonic. The displacement vectors of the nodes at rib groove were also extracted to explore the flow difference. Additionally, the rib height increased with ultrasonic. In conclusion, it is productive to apply ultrasonic into the ribbed cylindrical parts flow spinning process to enhance the forming quality of the inner longitudinal ribs.