these figures are only of a schematic nature and only promote an understanding of the present invention . the same elements are provided with the same reference numerals . fig1 shows a first specific embodiment of a hydraulic camshaft adjuster 1 according to the present invention . the hydraulic camshaft adjuster has a stator 2 , which is designed in the form of a cup in the exemplary embodiment shown here . a rotor 3 is accommodated in the interior of stator 2 . rotor 3 is rotatably mounted in relation to stator 2 about a common longitudinal axis 4 , which functions as the axis of rotation . stator 2 has a bottom 5 and a longitudinal wall 6 which extends completely around longitudinal axis 4 and is closed on the circumference . bottom 5 is an integral part of longitudinal wall 6 . a cover 7 is provided on the side opposite bottom 5 . an integral gearwheel 8 is also formed on stator 2 on the side of bottom 5 . gearwheel 8 is designed for coming into force - transferring contact with a traction means , such as a chain or a belt for transferring force from a crankshaft to stator 2 . rotor 3 has an insert area 9 for insertion of a central valve . two fluid lines 10 are recognizable in the sectional view in fig1 , although multiple fluid lines 10 are used . different cells of a cavity 11 situated between stator 2 and rotor 3 may be supplied with hydraulic fluid ( hydraulic oil ) in a targeted or directed manner . a connection 12 is formed between stator 2 and cover 7 on the side of cover 7 facing away from bottom 5 . this connection 12 is discernible in a particularly clear manner in fig2 . connection 12 is created by a rolling operation in which material of stator 2 has been formed / compressed around an edge of cover 7 . in the corresponding formation without machining , the material flows pressure - induced behind cover 7 . cover 7 is inserted fittingly or with an excess of fit into the cavity between a chamfer 13 and an inner wall 14 of stator 2 . cover 7 acts as a sealing cover . the material of stator 2 situated adjacent to cover 7 , in particular adjacent to chamfer 13 of cover 7 and on the end of stator 2 remote from the bottom in longitudinal wall 6 of stator 2 , has been forced into the aforementioned cavity between cover 7 and stator 2 by a rolling operation / formation without machining . the material of stator 2 has flowed into this cavity and completely fills the cavity . the end of stator 2 remote from bottom 5 protrudes beyond cover 7 ( protruding axially ). a recess 15 is formed there and may also be referred to as a groove or channel . fig3 shows the hydraulic camshaft adjuster 1 having a central valve which is not yet inserted into insert area 9 . fig4 through 6 illustrate an exemplary embodiment , which has been modified in comparison with fig1 through 3 . whereas stator 2 is designed in the form of a cup in the exemplary embodiment illustrated in fig1 through 3 , stator 2 in the second exemplary embodiment is designed in the form of a sleeve or bushing . it is designed in the manner of a hollow cylinder having a circular interior and exterior contour , circumferential grooves or channels for accommodating cover 7 being provided on the inner circumference at the ends . stator 2 thus has no bottom 5 but instead also has a cover 7 in this location but it is inserted into stator 2 as a locking cover having a locking contour , thereby forming a seal . as is also the case with cover 7 ( sealing cover ), which ( only ) forms a seal at a distance from the gearwheel , this second cover 7 ( locking cover ) is also in contact with a shoulder 16 of stator 2 , the shoulder being formed by the corresponding groove or channel . just as left cover 7 is attached to stator 2 via a rolled connection , right cover 7 is also attached to stator 2 via a rolled connection . the corresponding rolled connections extend around longitudinal axis 4 by 360 °.