Optimised writing flow with lubrication-free linear technology

At the heart of the handwriting robot are three linear axes that enable the movement of a biro. The positioning should be so precise that the robot can even imitate the nuances of given handwriting.

Two of the linear axes run parallel at a distance of around 50cm. Linear carriages move on their rails, holding a third linear guide and positioning it vertically. The pin is assembled on another carriage that moves horizontally on the third linear guide. The synchronised interaction of the axes enables it to reach any point on the writing field. When the pin starts to write, maximum mechanical precision is required - and this is where the search for the right components began.

Earlier models worked, but only slowly and were prone to wear. This led to high maintenance costs. The writing results were also unsatisfactory. The robots are used by a customer in a warehouse. As there are several robots and because the environment is quite dusty, the quietest possible operation and the absence of external lubricants were further important requirements for the components.

Our dry-tech linear technology finally met all the requirements. The solution is a combination of drylin T miniature linear guides with pre-loaded carriages, dryspin lead screws with cylindrical lead screw nuts and electric stepper motors.

The stepper motors realise precise movements of the carriages in the millimetre range via the lead screw drives at millisecond intervals. This high level of precision is made possible by the innovative geometry of the dryspin lead screw thread. The flank angles of the lead screw nut and lead screw are flattened, resulting in an above-average efficiency of 82 per cent, which supports the adjustment accuracy. In this way, very high precision is achieved when writing.

The linear technology not only makes the handwriting robot more precise, but also reduces maintenance, as it does not need any external lubrication. Solid lubricants are integrated into the plastic of the lead screw nuts and the sliding elements in the carriages, which are gradually released during operation and enable low-friction dry operation. Thanks to this self-lubricating effect, the robots can work fail-safe in the end customer's dusty warehouses. Unlike lubricated recirculating ball bearing and guideway systems, there is no risk of the ambient dust sticking to the lubricating grease and causing losses in the adjustment movements. And there is yet another advantage: the ball-free sliding systems are particularly quiet.

This means that the robots can write thousands of company greetings quietly, fatigue-free and without disruptive maintenance work.