Constrained forming of contoured composite hat stringers
AssigneeThe Boeing Company
InventorsSteven Joseph Plummer, Kurtis Shuldberg Willden, Megan E. Bliss
Life of this patent
Estimating the term…
Abstract
Cap wrinkling in a contoured composite hat stringer is reduced by constraining the cap as the hat stringer is being formed from a flat composite charge. The cap is constrained by an inflatable bladder placed in a tool set used to form the composite charge.
Claims20
A method of forming a contoured composite hat stringer having a contoured hat section including sides and a cap, comprising:
- placing a composite charge on a pair of dies mounted to a flexible bottom plate, the pair of dies forming a die cavity;
- installing an inflatable bladder within the die cavity, the inflatable bladder resting on the flexible bottom plate;
- inflating the inflatable bladder to completely fill the die cavity;
- forcing the composite charge into the die cavity with a punch mounted to a flexible top plate, the punch in contact with a first side of the composite charge;
- constraining the cap between the inflated bladder and the punch as the composite charge is being forced into the die cavity, the inflated bladder in contact with the cap from a second side of the composite charge;
- and
- applying pressure to outer edges of the composite charge with a pair of inflatable flange pinch bladders, the pair of inflatable flange pinch bladders positioned between the outer edges of the composite charge and the flexible top plate and in contact with the first side of the composite charge, wherein the applying pressure includes allowing the outer edges of the composite charge to slip over the pair of dies during the forcing the composite charge into the die cavity.
A method of forming a contoured composite hat stringer having reduced wrinkling, comprising:
- placing a composite charge on a pair of dies, the pair of dies forming a die cavity;
- installing an inflatable bladder within the die cavity;
- inflating the inflatable bladder to completely fill the die cavity and contact the composite charge;
- forming the composite charge into a contoured hat section having sides and a cap by forcing the composite charge into the die cavity;
- and
- reducing stress in the cap during the forming by constraining the cap with the inflated bladder as the composite charge is being formed.
A method of forming a contoured composite hat stringer having a hat section including sides and a cap, comprising:
- placing a flat composite charge on a pair of dies defining a die cavity;
- installing an inflatable bladder within the die cavity;
- inflating the inflatable bladder to completely fill the die cavity and contact the flat composite charge;
- forcing the flat composite charge into the die cavity to form a hat section of the contoured composite hat stringer having sides and a cap;
- constraining the cap with the inflated bladder as the flat composite charge is being forced into the die cavity;
- contouring the die cavity;
- and
- reducing wrinkling of the cap during forming of the hat section by transferring stress in the cap away from the cap.
Dependencies are inferred from the claim text.