A method of forming an annular textile preform by needling a helical fiber sheet, and a machine for performing such a method

Abstract

The invention provides a method of forming an annular textile preform by needling a helical fiber sheet, the method comprising in succession: unwinding a helical fiber sheet (8) from a horizontal sheet-forming turntable (6) driven at a constant and predefined speed of rotation NFS onto a horizontal intermediate unwinder (24) driven at a speed of rotation NDI and positioned on a horizontal intermediate turntable (22) driven at a speed of rotation NFI, unwinding the helical fiber sheet from the intermediate unwinder onto a final horizontal unwinder (12) driven at a speed of rotation NDF, and unwinding the fiber sheet from the final unwinder onto a horizontal preform-forming turntable (18) driven at a variable and predefined speed of rotation NFP so as to be subjected to needling thereon, the speeds NDI, NFI, and NDF being controlled in such a manner that NDF is proportional to NFP, NFI = (NFS - NDF) / 2, and NDI = (NFS + NDF) / 2.