Thread technology for birth simulator

3B Scientific GmbH provides the answer with the birth simulator "SIMone". The user of the simulator helps a plastic foetus to be born, with different scenarios each requiring specific procedures. The actual birth process is both recorded and predetermined with the help of a "force feedback" system: The foetus moves through the birth canal. The integrated force-torque sensor system measures the forces and directions with which the obstetrician brings the baby into the world and displays these actual values on the screen in comparison to the target values considered to be optimal, alongside medical data such as blood pressure - in real time. Breathing noises and expressions of pain from the lead screw nut are just as audible as the baby's heartbeat. The effect of medication such as paracetamol or a contraceptive drip is also simulated and the position of the child in the pelvis is displayed on the screen in 3D.
 
This process is fascinating for the layperson and highly instructive for the obstetrician. With SIMone, 3B Scientific GmbH has created a genuine innovation in its programme and has done a good service to expectant mothers and obstetrics in general. One example of many: SIMone is standard equipment in midwife training programmes in Cuba and the Cuban Ministry of Health cites the use of the simulator as one of the reasons for the country's extremely low birth mortality rate.

drylin® Linear bearing instead of recirculating ball bearing guide
Optimisation work was still required on the mechanical side - particularly on the linear axis, which determines the path through the birth canal. Swen Dressel, Head of Research & Development: "A recirculating ball bearing was planned here, but it had to be cleaned regularly because the lubricant required to simulate the birthing process drips into the unit. If it is not removed, the unit corrodes." As the users did not always follow the relevant maintenance instructions, this occasionally led to failures.
 
The developers therefore looked for an alternative - and found it with the drylin® system from igus®. These linear axes use a sliding pairing of hard-anodised guide rails and bushings made of the wear-resistant high-performance plastic iglidur® with incorporated lubricant. They therefore manage without lubrication, and contamination from lubricants does not impair their function.

Further drive elements were substituted
This solution has now proven itself to the complete satisfaction of the developers - and has led to further components being substituted by igus® bearings. Swen Dressel: "For the translational positioning of the foetus, we now use a drive rod consisting of an igus® lead screw and a backlash-lead screw nut."

The dryspin® lead screw technology is based on the principle of lubrication- and maintenance-free linear technology. The specifications and geometries of our lead screw technology, which are matched to the plastic nut and spindle, guarantee efficiencies of up to 82 % and a service life that is up to 30 % longer than conventional lead screws.
 
The worm wheel on the force feedback sensor, which causes the foetus to rotate and was originally made of brass, has also been replaced. "We still had to machine this component at great expense. Now we obtain a ready-to-install drawing part made of iglidur® from igus®, which has proven itself perfectly."

Conclusion: maintenance-free and cost-saving
As a result, the entire birth simulator is now maintenance-free. This brings advantages for the manufacturer and the users, who also benefit from the fact that the moving components no longer need to be greased. Swen Dressel: "The birth simulator is used in clean environments, for example in lecture theatres and teaching hospitals. Greased drive elements are not common or desirable there, especially as they can lead to soiling of clothing when the simulator needs to be cleaned."