Study of Hydroextrusion Method Without Mandrel for Medium-Carbon Steel Thick-Walled Tubes

Аннотация

Results are given for analytical an experimental studies of the method of hydroextrusion of thick-walled tubes of medium carbon steel without a mandrel. The aim of work is to determine the operating efficiency of the method as a whole and to check its application regimes. In order to achieve this aim, examples of numerical modeling by a finite element method in an ABAQUS system are used, and also deformation of a workpiece of actual material in a test industrial unit. The effect of degree of deformation and slope of the forming tool on liquid pressure required for changing the shape of a billet is established. It is revealed that during deformation there is thinning of a hollow billet wall, and the amount of relative wall thinning depends on the degree of deformation and die conical surface angle. It is established that compressive stresses operate at the inner contour of a hollow billet, but the outer contour stresses are tensile, and the zone of increase in deformation is adjacent to the inner contour of a hollow object. It is established that the method of hydroextrusion without a mandrel is most effective for manufacturing thick-walled hollow objects with an opening 0.5 to 3.0 mm in diameter and 100–500 mm long, and an increase in productivity by a factor of 3–5 is provided compared with deep drilling processes. A feature of the method is the possibility of automatic testing of hollow objects during manufacture under the action of liquid high pressure (higher by a factor of 3–5 than with operation of these objects). The application range for the method is precise treatment of hollow billets.