Method and apparatus for contracting a cylindrical body.

摘要

This invention provides a method and an apparatus for diametrically contracting a hollow cylindrical body (3) containing an element (2) inserted therein with a clearance therebetween, to thereby sealingly fit said hollow cylindrical body (3) to said contained element (2) by a diametrical contraction of the hollow cylindrical body (3), which method comprises the steps of: grasping the cylindrical body (3) with a plurality of elongated grasping members (4), preparing a cylindrical drawing die (5) having an opening at one end and a tapered inside peripheral surface (5a), drawing the grasping members (4) together with the cylindrical body (3) into the drawing die (5), through the opening, and applying a compression force to the cylindrical body (3) through the grasping members (4) due to the passage thereof through the tapered inside peripheral surface (5a), to thereby cause the cylindrical body (3) to be diametrically contracted. During the drawing process, since the cylindrical body does not come into direct contact with the drawing die, neither scratches nor baking cracks are produced on the outside surface of the cylindrical body.