A new bench for bending-fatigue tests of tempered steel wires is presented. The test bench is basically a four point bending machine. The main difference with current bending machines is that the new bench is devoted to test a semi-finished component more than a material. Actually, the new bench is used to check the spring wire just before it is finally employed to realize a spring. Typical applications of tempered wires are torsion spring bars or helical coil springs. It is of crucial importance to check the fatigue properties of tempered steel wires before the spring is manufactured, to assess and monitor the process performance.
The bench has some unreferenced features that make the it quite accurate and effective in producing quick fatigue assessments. The wire is loaded by means of rolling plastic bearing that reduce to the least extent the physical interaction of the component with the bench. Additionally, a rotor-dynamic study has allowed to perform tests at 50Hz.
As a preliminary application, we produce some fatigue bending tests of tempered steel wires.
Federico Ballo, Michele Carboni, Gianpiero R M Mastinu, Giorgio Previati