Profile section beams may for example produced by extruding aluminum, with one or more longitudinal channels, in connection with the outside via a likewise longitudinal slot opening. These channels may be used for joining two or more sections by means of screw joints and connector fittings, e.g. for building a stand frame.
It is known to use a type of screw joints with a nut means which is entered into the channel via the section end to act as an attachment for a screw which extends via the slot into the channel. With these joint systems it is difficult to make modifications of an existing frame, e.g. for attaching new sections in the direction upwards or to the side, because new nut means must be entered at the section end.
It is also known to use scew joints with a nut means which is s o designed that it in one position of rotation may be entered from the outside through the slot into the channel, after which it in another position of rotation, via protruding shoulders, form a locking inside the channel. Thus, these screw joints make it possible to enlarge an existing stand rapidly and efficiently, e.g. from the middle of a section.
One drawback with these known screw joints is that the nut means may be displaced, by vibrations or other unintentional influence from its locking position, wherein the screw joint may loosen. This may lead to damages to people and/or to machines.