METHOD OF ELECTROMECHANICAL MANDRELING Russian patent published in 2016 - IPC B23D43/00 

FIELD: technological processes.

SUBSTANCE: proposed method comprises displacement of mandrel with tension along bore axis and formation on the hole surface of strengthened ring areas with different hardness by heating them to hardening temperature with short-time passing of electric current through the point of mandrel contact with bore surface. During processing carbonising paste is applied on the bore surfaces at closed ring sections. This forms sections with hardening depth of 0.1…0.15 mm, with high hardness of 40…47 HRC_e, alternating with the same sections having hardness in several times smaller which wear out during operation thus forming channels for lubricant retention.

EFFECT: increased wearability and operation life of parts.

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