The world's first technology has been introduced for piecing hollows (tubes) of hard-to-deform hypereutectic silumin alloys (01390 and 01392). The tubes have the dimensions 80 mm diameter X 13.5 mm wall thickness and 74 mm diameter X 15 mm wall thickness. The are obtained on universal rotary rolling mill 20-60. The technology was developed by modeling the rotary rolling operation, studying the rheological properties of hypereutectic alloys, finding scientifically sound parameters (rolling scheme, feed angles, temperature-speed parameters) for an intermediate rotary-rolling operation performed to obtain bars with a crystalline structure and ductility properties 3-4 times better than those of the initial ingots, and the developing and introducing a piercing process that employs special spherical mandrels with a conical nose.
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