Fastening device and an unlocking and placement tool for such a fastening device

A fastening device comprising an outer tubular body, an axially slidable core placed within the tubular body, a spring member mounted inside the tubular body which at one end engages with the core and at the other end engages with the tubular body, at least one opening in the wall of the tubular body, and an axially slidable locking member which extends through the opening and is positioned in abutment against the core, wherein the core is provided on an upper end of the tubular body with an abutment surface which can engage with a tool for axial movement of the core between a locking position in which a locking part of the core lies in abutment against the locking member and a release position in which a relatively narrow release part of the core is disposed in a radial direction opposite the locking member, wherein the core is pressed in an upward direction by the spring member into the locking/securing position, wherein the core can be brought into the release position by pressing the spring in a downward direction, wherein the tubular body is provided on the upper end with a head surface which has a feed-through opening towards the abutment surface, the abutment surface being positioned in or beneath the head surface in the locking position, and wherein tubular body is provided on an outer side with a screw thread and a slidable clamping member which can be moved along the screw thread.