| 主权项 |
1. A method of manufacturing a beam of composite material having a variable H cross section along its length, the beam including a lower flange, a flat web and an upper flange, at least one of the flanges having a non-rectilinear profile when viewed in a longitudinal vertical plane, the beam having two end portions having a first height: an intermediate portion between the two end portions, the intermediate portion having a second height less than the first height, and two transition portions linking the intermediate portion to the end portions, the lower flange being inclined in the transition portions; the method including the steps of:
preliminarily assembling a beam of fibre-reinforced curable thermosetting composite material in an uncured condition; providing a lower forming tool having a lower forming surface having two lowered end portions, a raised central portion, and two linking inclines shaped to give the lower flange a predetermined shape; providing an upper forming tool having an upper forming surface shaped to give the upper flange a predetermined shape; providing releasable supporting means for supporting the upper tool above the lower tool with the upper and lower forming surfaces substantially aligned one above the other; providing a pair of longitudinally elongate rigid inserts which are axially symmetrical about longitudinal vertical plane, wherein each of the two inserts has a lower face with a profile congruent with or corresponding to a profile of the lower forming surface, the lower face having two lowered end sections, an intermediate raised section and two joining inclines; a flat rectangular upper face with a profile congruent with or corresponding to a profile of the upper forming surface, and a side face joining the upper and lower faces; enclosing each rigid insert in a respective airtight tubular bag; laying the uncured beam on the lower forming tool, provisionally resting the lower flange on the lower forming surface; fitting the two inserts into respective side spaces on two opposite sides of the web, between the upper and lower flanges, with the side faces of the inserts facing the web of the beam to be cured, and supporting the inserts with support means fixed with respect to the lower tool; positioning the upper forming tool above the upper flange of the beam, and supporting the upper forming tool with said releasable supporting means; sealing laterally spaces between the upper tool and the lower tool on the two opposite longitudinal sides of the beam by applying two respective outer lateral airtight films, both of the outer lateral airtight films being sealed to the upper forming surface of the upper tool and to the lower tool; sealing open opposite longitudinal ends of both of the tubular bags in such a manner that the pressure applied in an autoclave, in a subsequent curing step, will cause the tubular bags to swell, pressing the tubular bags against the two opposite faces of the web and against pairs of mutually facing surfaces of the upper and lower flanges; curing the beam in an autoclave by applying a programmed cycle of temperature and pressure; upon completion of the curing, releasing the releasable support means of the upper forming tool, removing the upper forming tool, and extracting the inserts from the beam transversely to the longitudinal direction. |
