| 摘要 |
Spherical balls, notably microballs of welding alloys, are produced by passing a melted material through vibrating orifices of a granulation pot, in order to form droplets which solidify when falling, by gravity, into a cooling tower filled with an inert gas. To improve the surface condition of the balls, the inert gas comprises approximately 15 to 150 ppm of oxygen. Moreover, the melted material is subject to ultrasound stirring just before being fed into the granulation pot. The balls are, preferably, dampened at the outlet of the cooling tower by brushes composed of polyamide wires. Besides, the control of the vibration frequency of the vibrating orifices in relation to the percentage of balls meeting the standards enables to improve the output.
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