52 u2032 in a spreader apparatus the fiber strand 2 is tensioned across the edge 54 and when the vibrations are applied will have a free space for vibrating due to the back set plane 55 fig3 c shows one possible arrangement of several such sonotrodes 52 u2032 a looping around the sonotrodes 52 as depicted in fig3 a 3 b 3 c is preferred for carbon fiber strands the fiber strand 2 is supplied at a steep working angle to the contact surface 53 u2032 53 u2033 53 u2032 u2033 of the sonotrodes 52 u2032 52 u2033 52 u2032 u2033 this is also possible when the first and third sonotrodes 52 are lowered with respect to the second sonotrode 52 as in the example of fig1 so that the contact surfaces 53 are no longer arranged at the same height but rather the first and third contact surfaces 53 are positioned lower in comparison to the second contact surface 53 fig4 depicts another exemplary embodiment in this example several fiber strands 2 are spread simultaneously that is several fiber strands 2 are guided side by side through the spreader device 5 and several spread fiber strands 2 u2032 that is fiber strands widened in the y direction leave the spreader unit 5 in order to obtain a single wide fiber strand 2 u2032 u2033 from these several spread fiber strands 2 u2032 the individually spread fiber.