Abstract: The invention relates to an appliance (8) for compacting, drying and cutting a preform of a hollow component of a turbomachine, said appliance comprising: a base (2, 2a) acting as a support for a sheet of material (1, 7) and comprising a long impression (22, 22a); a mandrel (3, 3a) which can be positioned in said long impression, clamping the sheet of material against the base, thus defining two flaps (12, 13, 72, 73) of said sheet (1, 7) arranged either side of the mandrel (3, 3a); and two side blocks (5, 6, 5a, 6a) which can be positioned such that they are supported on the base, either side of the mandrel, clamping the flaps of the sheet against the mandrel, said side blocks and/or the mandrel co-operating with means for cutting said flaps in such a way that they are adjusted to the dimensions of the mandrel or said side blocks.

Abstract: A fiber blank woven as a single piece by three-dimensional weaving to make a closed box-structure platform out of composite material for a turbine engine fan. In each plane of the fiber blank, a set of warp yarns interlinks layers of weft yarns in first, second, and third portions of the fiber blank, while leaving a closed non-interlinked zone separating the first and second portions over a fraction of the dimension of the fiber blank in the warp direction between an upstream non-interlinking limit and a downstream non-interlinking limit, and while leaving at least one open non-interlinked zone separating the second and third portions over a fraction of the dimension of the fiber blank in the warp direction from a non-interlinking limit to a downstream edge of the fiber blank. A method of fabricating a preform for the closed box-structure platform can use such a fiber blank.