Valve disc device, assembling method thereof, and exhaust gas turbocharger with valve disc device

The invention relates to a valve disc device for an exhaust gas turbocharger and an assembly method thereof, and an exhaust gas turbocharger having the valve disc device. The valve disc device includes a closing element having a disc portion and a retaining portion, a washer, a disc spring, and a main shaft. The main shaft is arranged on the holding portion between the disc portion and the washer.A disc spring having a plurality of centering adjustment pieces is clamped between a washer and a main shaft on a holding portion. Each centering adjustment piece has a centering molding with a contact point that points radially inward. The centering mouldings are pre-loaded by radial centering against the outer circumferential surface of the gasket at the corresponding contact points for centering. When the disc spring and the washer are clamped axially, the centering moulded parts bear against the circumferential surface with corresponding contact points, so that the radial preload is reduced compared to the center