PROCEDIMENTO PER LA FABBRICAZIONE DI PEZZI CAVI DI FORMA CILINDRICA

Hollow articles of cylindrical shape are produced by using electroslag remelting at a rate of 0.3-0.6 mm/s to obtain a hollow blank. Its surface is then strengthened by a plasma beam from a plasmatron with a current of 220-320 A, a relative motion between plasmatron and blank of 3-10 m/s and a gap of 2-10 mm. In the finishing stage, a magneto-abrasive treatment is applied to the surface, using vibrating pole shoes and ferromagnetic powder, with the prod. of the frequency of vibration and the travelled length equal to ten-times the linear velocity. To prepare a shaft of chrome steel of 400mm dia., 2500mm length and 15mm wall thickness, the blank was produced by electroslag remelting at a rate of 0.35 mm/s. The surface was strengthened by a plasma beam, using a current of 230 A at a speed of the blank of 9 mm/s and a gap between it and the plasmatron of 4mm. During the magneto-abrasive treatment the linear speed of rotation of the blank was 0.5 m/s, the pole shoes oscillated at a frequency of three per sec. and the travelled length was 0.1m. The magneto-abrasive treatment took 6-6 1/2 hrs. The achieved surface roughness was 0.04mm.