Collar (metal)
A bundle , in the plural bundles , refers to a frequently decorated, (profiled) metal band (mostly flat material) for firmly connecting metal rods.
The bundle is bent while glowing around the (bundled) rods, rods or tubes that are as close as possible to one another, in order to ensure that they are firmly bonded together without corrosion in the long term.
As a result of the warm connection, the surrounding metal band - the collar - shrinks when it cools. During the process , the bars are pressed together.
This process was "invented" by blacksmiths in the early Middle Ages in the Romanesque period at the latest in order to save the time- consuming fire welding or perforation in the manufacture of grilles and at the same time to set a decorative accent.
In the past, the collar was made quite solid by overlapping and welding the ends or form-fitting ends (for example: dovetail connection ). The individual leaves of a leaf spring are also held together by a collar (spring collar or spring clip).
In today's mostly machine-made decorative work such. B. Lattice, the "bundle" is mainly used as a less rigid connection and "cold" bent together. Art blacksmiths, on the other hand, still use the technology for custom-made work today to firmly connect semi-finished products , e.g. B. in winding technology.
Full-surface welded collars are z. B. used industrially to produce sharp-edged thickenings on shafts or other components (see shaft collar ).
Screw heads were also sometimes designed as a collar around the screw shaft if the difference in cross-section or the total length made upsetting the head problematic, a technique that is practically no longer used today.