SDS100

Problem

The quality of a cable crimp can be evaluated by the force gradient curve during the crimping process. Available sensors on the market are optimised to reproduce only this specific force gradient curve as accurately as possible.

In addition to the force gradient curve, a crimping machine manufacturer would like to measure real, absolute forces during crimping. Since available sensors are insufficient for this task, a new sensor is to be developed.

A strain gauge will be used as a sensitive element to be able to measure absolute values of the applied forces. The sensor shall be equipped with an integrated measuring amplifier. The geometric dimensions of the sensor are fitted to the mounting position on the used crimping press. Based on the service life of the crimping press, the sensor must withstand at least 100 million crimps, and thus elongation cycles.

A very wide measuring range is mandatory for the sensor to be able to cover all wires with different cross-sections that are processed on the same crimping press without adaptation (small cable cross-sections cause small forces and thus small elongation whereas large cable cross-sections induce large forces and thus large elongation). To ensure that the evaluation of the crimp quality works equally well over the entire range of diameters, the sensor must have an extremely low signal-to-noise ratio. In addition, it needs to have a high measuring accuracy and repeat accuracy.

Answer

The new SDS100 sensor was developed in cooperation with our customer according to their specifications. The progress of the project was regularly checked and verified by using prototypes. The entire development project included the following points:

  • Design of the spring bellow
  • Analysis and selection of a suitable strain gauge
  • Development of a very small and low-noise measuring amplifier (with partner company)
  • Development of a potting process to protect the strain gauge and measuring amplifier
  • Planning and implementation of the production processes
  • Implementation of series production