a controlled manner when using a u201c thick u201d screw that is to say a fastening screw having a shaft diameter that is greater than the first region 18 fig9 is a sectional view of a third embodiment of a hollow shaft the third embodiment of the hollow shaft 14 shown in fig9 differs from the hollow shaft 14 known from fig7 in particular by the conical tapering of the first region 18 which may also have outside the narrowing portion 30 a diameter which decreases starting from the second region 20 and the step 28 fig1 is a sectional view of a fourth embodiment of a hollow shaft the fourth embodiment shown in fig1 differs from the third embodiment known from fig9 by a particular configuration of the grooves 40 in the region of the narrowing portion 30 in the fourth embodiment shown in fig1 the grooves 40 are raised further towards the plate 12 on the outside of the hollow shaft 14 so that a particularly controlled expansion of the tip of the hollow shaft 14 is possible when a correspondingly dimensioned fastening screw is pre mounted fig1 is a sectional view of a fifth embodiment of a hollow shaft the fifth embodiment shown in fig1 comprises an indentation 54 in the region of.