Method and device for deforming a workpiece made of a material having an exponential tensile stress-strain behavior into a thin-walled, hollow shell

A device for forming a workpiece of a material having an exponential tensile stress-strain behaviour into a thin-walled, hollow shell, comprising:

• a clamping device rotatable about center line for clamping the periphery of the workpiece;
• a drive for rotating the clamping device about the center line;
• a spinning die which is freely rotatable about the center line, is movable in the direction of the center line, and is designed to exert a predefined pressure force against the workpiece;
• at least one path-controlled spinning roller opposite the spinning die;
• a first control device for controlling the at least one spinning roller in a path-controlled manner;
• and
• a second control device which ensures that the relative velocity between the workpiece and the at least one spinning roller and the force exerted on the workpiece by the at least one spinning roller and the spinning die are matched to one another such that the tension forces applied to the workpiece are less than the yield strength of the material of the workpiece.

A method for forming a workpiece blank of a material into a thin-walled, hollow shell comprising:

• clamping the workpiece blank on its periphery and actively rotating it about its center line;
• pressing a freely rotatable spinning die having an external side with the desired shell shape with a suitable pressure force against a workpiece side;
• pressing at least one path-controlled spinning roller against the other workpiece side so that the rotating workpiece is formed into shell exclusively by local pressure forces, the relative velocity between the workpiece and the at least one spinning roller and the force exerted on the workpiece by the at least one spinning roller and the spinning die being matched to one another such that tension forces applied to the workpiece are less than the yield strength of the material of the workpiece;
• heating the workpiece blank to a processing temperature below the known hot-forming temperature for this material at least in the partial areas contacted by the spinning rollers.

A device for forming a workpiece of a material having an exponential tensile stress-strain behaviour into a thin-walled, hollow shell, comprising:

• a clamping device rotatable about a center line for clamping the periphery of the workpiece;
• a drive for rotating the clamping device about the center line;
• a spinning die which is freely rotatable about the center line, is movable in the direction of the center line, and is designed for exerting a predefined pressure force on the workpiece;
• at least one path-controlled spinning roller opposite the spinning die;
• a first heating device designed for heating at least the workpiece area in which the at least one spinning roller contacts the workpiece;
• a first control device for controlling the at least one spinning roller in a path-controlled manner;
• and
• a second control device which ensures that the relative velocity between the workpiece and the at least one spinning roller and the force exerted on the workpiece by the at least one spinning roller and the spinning die are matched to one another such that the tension forces applied to the workpiece are less than the yield strength of the material of the workpiece.