The invention relates to the clinching of thick metal workpieces for producing load- bearing clinch connections, the use of corresponding clinch connections in steel construction, as well as correspondingly produced steel construction elements, particularly for use in escalators, moving walkways or lift installations.
Clinching is a deformation joining method already known for a long time. This method is also termed penetration joining. Clinching is a deformation-based connecting technology which depending on the respective form of embodiment manages without any auxiliary joining component.
For clinching there are different variants with respect to production of the joining element. Characterization of clinching is possible in accordance with the following:                according to the joining element construction: clinching with and without a cutting component;        according to the matrix shape: solid and open matrices        according to the tool kinematics: single-step and multi-step clinching.        
In the following the primary concern is clinching without a cutting component. This method has certain advantages relative to the conventional method used for connecting plates or other workpieces, such as, for example, welding, spot-welding, connecting by means of rivets or blind rivets and use of punch rivets. By comparison with conventional connecting methods, clinching without a cutting component is more advantageous when the costs per connection are taken into consideration.
The clinching of plates and other metal workpieces thicker than 4 millimeters is known from US 2006/0096075 A1. As was established within the scope of the present invention, however, the clamping forces in this known method are very high, which on withdrawal of the die can lead to damage of the plates or metal workpieces.