Strain transmitters are, for example, mounted on machine structures in order to monitor processes. In the case of injection moulding machines, for example, the closure force of the moulding tools is monitored with strain transmitters, whereby strain gauges are generally used for this purpose. These deliver very reliable measurements for large strains that originate from large forces, such as those that occur as the tools dose. However, it should also be possible, on the other hand, to measure very small forces, During the movement a so-called mould protection function is designed to protect the tool from damage, in that the closure of the mould parts is stopped immediately if a component has not been correctly removed from the mould. For this purpose it must be possible to register the smallest forces with respect to strains on the tool.
Strain gauges can register small strains less well. Piezoelectric strain transmitters, on the other hand, are excellently suitable for the registration of both small and large strains, but unfortunately they cannot conduct static measurements.
In GB 1456403 an S-shaped strain transmitter is specified, which features centrally a chip with a measuring bridge, and which can deduce the strain on the basic structure on the basis of the shear stress determined. It has been shown that making contacts with such a chip is very cumbersome.