Method of manufacturing a cylindrical housing of an exhaust gas treatment unit and method of manufacturing an exhaust gas treatment unit for vehicles

A method of manufacturing a cylindrical housing of an exhaust-gas treatment unit for vehicles, comprising the steps of:

• a) providing a sheet metal part that is flat and has at least one embossing;
• b) round bending the sheet metal part in a round bending tool by displacing the sheet metal part between rolls such that the sheet metal part obtains a cylindrical shape having a longitudinal direction parallel to roll axes of the rolls, and with at least one elastic roll being used such that the at least one embossing of the sheet metal part is maintained during round bending, and wherein the rolls comprise at least three rolls that are used for the round bending, the at least three rolls including at least one upper roll and one lower roll, with at least one roll being driven, and the sheet metal part being displaced several times back and forth between the rolls, and the at least one upper roll and the at least one lower roll being spaced from each other in different manners in the individual displacement steps;
• and
• c) connecting longitudinal edges of the sheet metal part to form a tube.

A method of manufacturing an exhaust-gas treatment unit for vehicles, comprising the steps of:

• manufacturing a cylindrical housing by
• providing a sheet metal part that is flat and has at least one embossing;
• round bending the sheet metal part in a round bending tool by displacing the sheet metal part between rolls such that the sheet metal part obtains a cylindrical shape having a longitudinal direction parallel to roll axes of the rolls, and with at least one elastic roll being used such that the at least one embossing of the sheet metal part is maintained during round bending, and wherein a projection side of the at least one embossing only comes into contact with the at least one elastic roll;
• and
• connecting longitudinal edges of the sheet metal part to form a tube;
• inserting an insert into the cylindrical housing which is circumferentially closed;
• and
• fastening covers to end faces of the cylindrical housing.