FIELD: rolled stock production. SUBSTANCE: apparatus, mounted under a screw-down mechanism, has two mutually opposite plates, connected one with another by flexible envelope in the form of bellows, whose transition near-edge portions, rested upon adjacent shaped surfaces of the plates, are welded to them. The envelope has in its mean part free toroidal convex-to-outside portions. A closed working chamber is formed between the plates, the chamber is connected with a high pressure manifold. The plate have annular cavities, into which the n ear-edge portions of the envelope are embedded with a gap along a thickness and a depth, being no more, than 1% of thickness of the envelope. EFFECT: enhanced reliability. 12 cl, 7 dwg
