OPTIMIZATION OF THE FORMING SEQUENCE OF A THREADED INSERT WITH GROVES BY MEANS OF FEM SIMULATION

In this paper the forging sequence of a new type of threaded insert is investigated by means of FEM simulations and subsequently optimized in order to decrease the number of operation. In fact, if the standard forging sequence of inserts without groves is used, an external heat treatment is usually realized after the product forming thus requiring a further forging operation after the H.T. for grooves formation. A new manufacturing sequence is here proposed and investigated: five forming operations including groves forging are sequentially realized then the complete annealing is realized at the end of the cycle. FEM simulation showed that the material hardening during groove formation strongly influenced the insert deformation during fastening and, in order to shift the annealing treatment at the end of the sequence, the shape of the deformation chamber needs relevant geometry modification. A FEM campaign was therefore performed in order to analyze the behaviour of the insert during the fastening phase on different sheets thickness, following different possible forging sequences. A pre-series of the developed inserts following the optimized sequence is then produced and tested: the grooved inserts properly fastened the required sheets range and the shape of the deformed inserts accurately matched the simulated geometry.