METHOD FOR AIR EXTRACTION WITH SEVERE PLASTIC DEFORMATION AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2017 - IPC B21D22/20 

FIELD: technological processes.

SUBSTANCE: hollow workpiece is pushed through two or more matrices arranged one above the other coaxially with the punch, with a successive reduction in the wall thickness. Multiple severe plastic deformation is provided with a periodically perimeter-changing coefficient and obtainment of a wall varying in the thickness perimeter with moulding of a hollow workpiece on the outer surface along the generatrix of projections and depressions. The subsequent retraction of the workpiece through the second matrix is also carried out with a perimeter-variable clearance between the punch and matrix with a wall thinning only at the sections of the workpiece having projections, and at the final stage the wall is deformed in the matrix with a uniform clearance between the instrument equal to the wall thickness of the finished shell. Matrices with a contour of the work hole made with a periodically changing profile are used, and the working contour of the last matrix forms a clearing with the punch uniform in perimeter, equal to the wall thickness of the finished shell.

EFFECT: coefficient of thinning is reduced and a fine-grained structure is provided.

2 cl, 4 dwg