Gear grinding machine

The invention relates to a gear grinding machine for carrying out a continuous tumbling process, comprising: a tool holder (1) having a worm wheel (3) which rotates about a worm wheel axis; at least one rotating workpiece holder in which a workpiece rotating about a workpiece axis is clamped; and a dressing unit (8) for dressing the worm grinding wheel (3), which produces teeth in the workpiece ina gear grinding step, and in a dressing step dresses a worm grinding wheel profile (12) interacting with the workpiece, which worm grinding wheel is a multi-zone grinding tool having at least two worm grinding wheel profile segments, different process steps can be carried out by means of the worm grinding wheel profile section. According to the invention, the dressing unit has at least two dressing tools that can be activated independently of one another, a first dressing tool (17) being associated with a first worm wheel profile section and a second dressing tool being associated with a second worm wheel profile sec