| 摘要 |
A method for manufacturing hollow forged pieces and a forging system for carrying out said method. Said method is used for forging hollow forged pieces of circular cross section from various steels, alloys and non-ferrous metals in four-die forging devices in press-forging works. A conical mandrel (8) is mounted with a clearance into a cavity in a blank (9), for which a ratio between corresponding diameters is maintained, the forging is carried out in two stages, in the first of which the blank is pressed until sections of the internal surface thereof make contact with the surface of the mandrel, and, in the second stage, sections of the blank are plastically deformed on the mandrel, and, during each pressing action, the mandrel is moved downwards such that the longitudinal axis thereof is displaced by a displacement value d of the longitudinal axis of the blank. For this, the mandrel is mounted so as to be movable along, and transversely with respect to, the longitudinal axis of the blank, and each die (5, 10-12) does not project beyond the limits of the working part (8) of the mandrel and has a calibration section (25) and an entry section (24) at an angle of 130-180°. The productivity, reliability and service life of the equipment are increased, the quality of the forged pieces enhanced, and mandrel forging folds are eliminated.
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