# US 2022/0080649 A1 · Constrained Forming of Contoured Composite Hat Stringers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2022/0080649 A1 - Document ID: US20220080649A1 - Status: Published application - Kind: A1 - Application number: 17/447,593 - Filed: 2021-09-14 - Published: 2022-03-17 - Earliest claimed: 2020-09-17 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Steven Joseph Plummer; Kurtis Shuldberg Willden; Megan E. Bliss - Web page: https://patentgrep.com/patent/US20220080649A1 ## CPC - B29C 51/28: for applying pressure through the wall of an inflated bag or diaphragm - B29C 70/342: {using isostatic pressure} - B29C 33/202: {Clamping means operating on closed or nearly closed mould parts, the clamping means being independently movable of the opening or closing means (clamping devices for injection moulding machines B29C45/64)} - B29C 33/505: {cores or mandrels, e.g. inflatable (B29C33/0016 takes precedence; for winding and joining B29C53/824; for supporting articles during joining B29C66/634; flexible cores for vulcanizing tyres B29D30/0654)} - B29C 51/004: {Textile or other fibrous material made from plastics fibres (combined with plastic layers B29C51/145; compression moulding of reinforced plastic articles in matched moulds B29C70/46; using pressure difference B29C70/44)} - B29C 51/087: {with at least one of the mould parts comprising independently movable sections (B29C51/32 and B29C51/34 take precedence)} - B29C 51/20: having movable moulds or mould parts - B29C 53/382: {using laminated sheets} - B29C 53/40: for articles of definite length, i.e. discrete articles - B29C 70/30: Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core - B29C 70/34: and shaping or impregnating by compression {, i.e. combined with compressing after the lay-up operation} - B29C 70/446: {Moulding structures having an axis of symmetry or at least one channel, e.g. tubular structures, frames} - B29C 70/462: {Moulding structures having an axis of symmetry or at least one channel, e.g. tubular structures, frames} - B29D 99/0003: {Producing profiled members, e.g. beams} - B29D 99/0014: {provided with ridges or ribs, e.g. joined ribs} - B64C 1/064: {Stringers; Longerons} - B64F 5/10: Manufacturing or assembling aircraft, e.g. jigs therefor - B29C 2033/205: {mould clamping by membranes, e.g. inflatable membranes or cushions} - B29C 2043/3649: {Inflatable bladders using gas or fluid and related details} - B29K 2821/00: Use of unspecified rubbers as mould material - B29K 2995/0082: Flexural strength; Flexion stiffness - B29L 2031/003: {having a profiled transverse cross-section} - B29L 2031/3076: {Aircrafts (blades, propellers B29L2031/08)} - B29L 2031/3082: {Fuselages} - B64C 2001/0072: {from composite materials} - Y02T 50/40: Weight reduction - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - B64C: AEROPLANES; HELICOPTERS - B64F: GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## 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. ## Claims ### Claim 1 Apparatus for making a contoured composite hat stringer, comprising: a pair of dies configured to be contoured along a length and defining a die cavity into which a composite charge may be formed into a contoured hat section having a cap; a punch configured to form the composite charge into the die cavity; and a bladder located within the die cavity and configured to constrain the cap as the contoured hat section is being formed. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the bladder is formed of an elastomer. ### Claim 3 (depends on 1) The apparatus of claim 1 wherein the bladder has a rigidity sufficient to constrain the cap as the composite charge is being formed. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the bladder is located between the dies and beneath the composite charge. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the bladder includes reinforcement in an area of the bladder facing the cap. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the bladder is sized to completely fill the die cavity when the bladder is inflated. ### Claim 7 (depends on 1) The apparatus of claim 1, further comprising: a controller configured to coordinate operation of the punch with inflation of the bladder. ### Claim 8 A method of forming a contoured composite hat stringer having reduced wrinkling, comprising: forming a composite charge into a contoured hat section having sides and a cap by forcing a composite charge into a die cavity; and reducing stress in the cap during the forming by constraining the cap as the composite charge is being formed. ### Claim 9 (depends on 8) The method of claim 8, further comprising: placing the composite charge on a pair of dies, and wherein forcing the composite charge into the die cavity includes using a punch to punch the composite charge into the die cavity while constraining the cap. ### Claim 10 (depends on 9) The method of claim 9, further comprising: using the dies to apply pressure to the sides of the hat section as the composite charge is being punched into the die cavity. ### Claim 11 (depends on 9) The method of claim 9, further comprising: contouring the hat section along a length of the hat section. ### Claim 12 (depends on 8) The method of claim 8, wherein constraining the cap includes: inflating a bladder, and using the bladder to apply a force against the cap. ### Claim 13 (depends on 12) The method of claim 12, wherein inflating the bladder is performed before forcing the composite charge into the die cavity. ### Claim 14 (depends on 8) The method of claim 8, wherein: forming the hat section includes contouring regions of the hat section along a length of the hat section, wherein the forming produces stresses in the cap along the regions, and reducing the stresses in the cap includes sweeping the stresses from the cap in the regions to other areas of the hat section. ### Claim 15 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; forcing the flat composite charge into the die cavity to form a hat section of the stringer having sides and a cap; 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. ### Claim 16 (depends on 15) The method of claim 15, wherein reducing wrinkling of the cap includes constraining the cap. ### Claim 17 (depends on 15) The method of claim 15, wherein transferring stress away from the cap includes applying pressure against the cap from within the die cavity. ### Claim 18 (depends on 15) The method of claim 15, wherein the contouring is performed before forcing the flat composite charge into the die cavity. ### Claim 19 (depends on 15) The method of claim 15, wherein the contouring is performed after forcing the flat composite charge into the die cavity. ### Claim 20 (depends on 15) The method of claim 15, wherein applying pressure against the cap is performed by: inflating a bladder within the die cavity, and using the bladder to apply a force to the cap.