In the woodworking industry, joints are increasingly screwed together using automated machinery rather than nailed together. Handling screws that are longer than 80 mm (3-1/8") is an art that not everyone can master. Stein-Automationstechnik , based in Wolfratshausen, Germany, specialises in this.

Needs

How can screws with a length of 80–380 mm (3-1/8" - 15") be fed in fully automatically at positioning speeds of up to five metres per second without getting caught? How can you screw XXL wooden components together in just a few seconds? These are questions facing Andreas Stein, master precision mechanic and owner of Stein-Automationstechnik. This is also the case for a Swiss manufacturer of prefabricated houses.

The technological requirements of Stein-Automationstechnik call for a supplier that not only supplies extremely robust cylinders, valves, guides and drives, but is also able to provide intensive advice and is prepared to jointly develop custom solutions. So it was a matter of course to develop the Stein linear unit with a special flange for the 30 Nm motor of the Swiss customer.  It took Stein less than a week to have the drawings and quotations on the table.

Solutions

Electric drives are characterised by a high degree of flexibility and infinitely variable controllability. This means Stein-Automationstechnik is no longer limited to one screw length, but can use several screw lengths in the same system. The Series 5ES linear axes achieve a positioning accuracy of 50 µm.  The torque can also be precisely adapted to the type of screws and material. The electrical solution is recommended for safety reasons, as no unexpected movement of the workpiece or other components can occur. The only pneumatic component in the Swiss machine is a cylinder that serves to separate the screws and feed them in with the help of the vibration plate.

Results

The Series 5ES linear axis is the heart of the Swiss solution: "The most suitable and fastest unit is the one from Camozzi," Stein points out. The 30 Nm motor should screw the screws into the timber walls in just 4–5 seconds – now it can be done in 3 seconds. Since the 5ES linear axis is extremely stable, it can also be used safely with powerful and heavy 5000 rpm and 30 Nm motors and with a repeat accuracy of around 0.5 mm. The linear unit is also robust enough to work flawlessly for many years under constant stress from heat and chips. A stainless steel sealing strip is used to seal the profile to the outside. This and a felt wiper behind the plastic cover ensure that no chips get inside the axis. 

Stein does not yet know what challenges the next project will bring, but one thing is already clear: "if at all, then only with Camozzi!" confirms the entrepreneur.