Equipment and process for making a structural element in composite material

1 . An equipment for making a structural element of composite material having a longitudinal axis and an axial cavity, said equipment comprising:

a support frame; and

a laminating mandrel, which is mounted on said support frame in a rotatable manner about a central axis and defines an outer laminating surface for laminating one or more layers of composite material to be cured or pre-cured into the structural element;

wherein said support frame includes:

two vertical headers, facing each other and parallel to each other, extending in use transversely to said central axis of said laminating mandrel and capable of accommodating between them the laminating mandrel; and

longitudinal connecting means for longitudinally connecting said headers;

each header comprising a fixed portion and a movable portion, coaxially receiving said laminating mandrel and rotatable about said central axis with respect to said fixed portion;

wherein said laminating mandrel comprises:

a central shaft defining said central axis;

a plurality of sectors angularly spaced apart about said central axis; and

a plurality of linear actuators each extending between said central shaft and a respective sector of the plurality of sectors to move the sectors between an expanded laminating position, in which said sectors are adjacent to each other at the maximum distance from said central shaft and define said laminating surface, and a contracted position, in which said sectors are adjacent to said central shaft and partially overlapping each other;

wherein said equipment also comprises:

first constraining means for connecting in a releasable manner said sectors in said expanded laminating position to said movable portions of said headers; and

second constraining means connecting each of said linear actuators to the respective sector in a releasable manner so as to enable the extraction of said central shaft and said linear actuators from remaining parts of said equipment in the condition in which said sectors, arranged in said expanded laminating position, are connected to said movable portions of said headers by means of said first constraining means.

2 . The equipment according to claim 1 , wherein said movable portion of at least one of said headers has a central opening through which said laminating mandrel or an assembly formed by said central shaft and said linear actuators can be inserted in and extracted from said support frame.

3 . The equipment according to claim 2 , wherein said headers further comprise gripping members, which are movable between a resting position, in which they are stowed within each respective header, and an operating position, in which they protrude from each respective header and hold the opposite end edges of the cured structural element to allow the extraction of said laminating mandrel from said cured structural element through said central opening.

4 . The equipment according to claim 3 , wherein said gripping members are movable between said resting and operating positions parallel to said central axis.

5 . The equipment according to claim 3 , wherein said gripping members are carried by the movable portion of each header.

6 . The equipment according to claim 3 , wherein the extraction of said laminating mandrel from the cured structural element occurs upon displacement, by said linear actuators, of said sectors from said expanded laminating position to said contracted position.

7 . The equipment according to claim 1 , wherein each linear actuator comprises a tubular sleeve, fixed externally to said central shaft, and at least one rod sliding with respect to said tubular sleeve to set positions protruding by different amounts from the tubular sleeve; and wherein the maximum stroke of said at least one rod of each linear actuator can be adjusted as a function of the conformation of the sectors and the maximum radial footprint of the laminating surface defined by the sectors.

8 . The equipment according to claim 7 , wherein said for each linear actuator, the second constraining means comprises a free end head of the at least one rod releasably coupled with an engagement seat of the respective sector.

9 . The equipment according to claim 1 , wherein each header is mounted on guide uprights allowing for height adjustment.

10 . The equipment according to claim 9 , wherein said guide uprights protrude inferiorly from each header to define respective support feet of said support frame, and wherein said longitudinal connecting means are provided with wheels to enable the equipment to be moved after the sliding of the headers on the respective guide uprights until the wheels themselves are brought into contact with the floor surface and at the same time said support feet are made to disappear.

11 . The equipment according to claim 1 , wherein said longitudinal connecting means comprise at least one pair of longitudinal crosspieces extending between said headers and having adjustable lengths.

12 . The equipment according to claim 1 , wherein said central shaft comprises a base module and one or more auxiliary modules axially couplable to one or both ends of the base module or to the auxiliary module(s) already assembled to increase the axial length of the central shaft.

13 . A process for making a structural element of composite material having a longitudinal axis and an axial cavity by means of the equipment according to claim 1 , said process comprising the steps of:

(a) connecting said sectors to said linear actuators and arranging the sectors in said contracted position on said central shaft;

(b) mounting the laminating mandrel with the sectors in the contracted position on said support frame;

(c) moving, by means of the linear actuators, said sectors into said expanded laminating position;

(d) connecting said sectors in the expanded laminating position to the movable portions of said headers by means of said first constraining means;

(e) releasing said second constraining means to disconnect said linear actuators from said sectors;

(f) retracting said linear actuators toward the central shaft;

(g) extracting the central shaft with the retracted linear actuators from said support frame;

(h) laminating with uncured or pre-cured composite material said laminating surface of said sectors;

(i) transporting the support frame and the sectors attached to it together with the laminated composite material to an autoclave to perform a cure cycle to form the structural element;

(l) taking the assembly of step (i) out of the autoclave;

(m) re-inserting the central shaft with the linear actuators inside the sectors and connecting the linear actuators to the sectors by means of said second constraining means;

(n) attaching the cured structural element to said headers;

(o) retracting, by means of the linear actuators and with the second constraining means active, the sectors into the contracted position on said central shaft; and

(p) extracting the laminating mandrel with the sectors in the contracted position from the cured structural element and support frame.

14 . The process according to claim 13 , wherein said step (n) is carried out by moving said gripping members into the operating position, in which they hold opposite end edges of the cured structural element thereby securing them to the headers.