METHOD OF CREATING A COMPOSITE ANGULAR CONNECTING ELEMENT BASED ON SOLID-WOVEN 3D PREFORM WITH CHANGE IN REINFORCEMENT STRUCTURE Russian patent published in 2024 - IPC B29C70/48 D06C7/02 

FIELD: moulding materials.

SUBSTANCE: can be used to create angular connecting element in form of bracket based on composite material with polymer thermosetting matrix. Reinforced 3D solid-woven preform with reinforcing structure forming transition from preform base is made. Preform comprises intertwined four layers of warp threads, five layers of weft threads and a piercing system of threads passing through four layers of the preform base due to change of the reinforcement structure to the outgoing layer. Outgoing layer includes intertwining one layer of warp and one layer of weft threads. Future stiffening rib of the composite material includes four bonded woven layers due to the fact that zones of the outgoing layer are staggered relative to each other when folded. At the first stage, three-dimensional solid-woven 3D preform is made on the basis of continuous carbon threads. At the same time transition from base of solid-woven 3D preform to outgoing layer for future stiffening rib is made with change of reinforcement structure so that the orthogonal weave warp threads, lying horizontally in a straight line in the upper fourth layer of the base of solid-woven 3D preform, change the trajectory, are separated from the middle of the fourth layer of the base of the preform and enter the linen weave of the outgoing layer, preventing pull-out of warp threads and shedding of weft threads of exit layer during further cutting of auxiliary weft threads located at edges and centre of outgoing layer. At the second stage, auxiliary weft threads are cut, enveloping the side parts of the preform, by means of which the transition from the fourth layer of the base of the preform to the fifth outgoing layer is made, and bonding the outgoing layer zones of the preform to each other, along three cutting lines. As a result, the outgoing layer of the preform is divided into four zones. At the third stage, 3D preform is folded twice into the final shape of the article. In the process of the first folding along the first fold line, four zones of the outgoing layer obtained as a result of cuts of auxiliary weft threads at the second stage are opened and preliminary pairwise combination is performed. In the process of the second folding along the second bending line the opened zones of the outgoing layer of the preform are turned in a staggered order. At the fourth stage, tooling mould is made for formation of angular connecting element in the form of bracket. At the fifth stage, folded 3D preform is laid in the tooling mould and impregnated with the binder by the RTM method. At the same time four zones of outgoing layer are transformed into stiffening rib consisting of four woven layers. At the sixth stage, after hardening by the binder, the finished product is removed from the tooling mould. Flash of the outer contour is removed. Through technical holes are formed. Stiffening rib shape is transformed. Chamfers are stitched in angular zones of the bracket.

EFFECT: disclosed is a method of making a composite angular connecting element based on solid-woven 3d preform with a change in the reinforcement structure.

1 cl, 11 dwg