Connecting device for profiled bars with grooves

A connecting device for connecting at least a first profiled bar and a second profiled bar that are essentially perpendicular to one another and have grooves, comprising:

• at least one sliding block positioned to slidably engage the second profiled bar;
• a plate connector unit having at least on recess, said plate connector unit being arranged proximate to the at least one sliding block;
• at least one screw unit extending in said recesses in the plate connector unit such that, along with the at least one sliding block, the plate connector unit is fastened to an end of the first profiled bar and anchored in a groove in the second profiled bar by the at least one screw unit,
• wherein one of a geometry of a screw head of the at least one screw unit is configured such that the screw unit is centered within the groove in the first profiled bar and a geometry of a shank of the at least one screw unit is configured such that the at least one screw unit is centered when engaged with the groove in the second profiled bar;
• and
• wherein a cylindrical shank of the at least one screw unit has an outer surface that abuts a surface of the groove in the second profiled bar, and when the cylindrical shank of the at least one screw unit is inserted into the plate connector unit, the cylindrical shank projects, at least in some areas, into the groove in the second profiled bar, the screw head has a cylindrical contour which rests, along three envelope lines, with a centering effect on an inner contour of the groove in the first profiled bar, and the plate connector unit has a planar upper and lower surface along its entire surfaces.