# US 11,897,210 B2 · Caul plate system for aircraft fabrication > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,897,210 B2 - Document ID: US11897210B2 - Status: Granted - Kind: B2 - Application number: 17/454,265 - Filed: 2021-11-10 - Published: 2022-05-19 - Granted: 2024-02-13 - Earliest claimed: 2020-11-18 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Daniel R. Smith; Darrell D. Jones; Byron James Autry; James R. Kendall; Raviendra Sidath Suriyaarachchi - Web page: https://patentgrep.com/patent/US11897210B2 ## CPC - B29C 70/549: {Details of caul plates, e.g. materials or shape} - 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 70/342: {using isostatic pressure} - B29C 70/44: using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding - B29C 70/443: {and impregnating by vacuum or injection} - B29D 99/0014: {provided with ridges or ribs, e.g. joined ribs} - B29L 2031/3085: {Wings} - 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) - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES ## Abstract Methods and apparatus involved in the process of hardening a composite part are disclosed herein. The methods include applying a preform to a mandrel, covering the preform with a caul plate, sealing the caul plate to the mandrel, pushing the caul plate toward the preform and the mandrel and hardening the preform into a composite part while the caul plate is held against the preform. The apparatus include a mandrel, a caul plate which defines a surface of a preform and where the caul plate may include a rigid material and seals disposed between the mandrel and the caul plate. In an additional aspect, the apparatus may include a sealed chamber with a mandrel and a caul plate and a circumferential seal between the mandrel and the caul plate. ## Claims ### Claim 1 A method for hardening a preform of fiber reinforced material, the method comprising: applying a preform to a mandrel; covering the preform with a caul plate; vacuum sealing the caul plate to the mandrel via a first circumferential seal in a clean room environment, the first circumferential seal disposed between the mandrel and the caul plate in a channel formed in the mandrel; inserting a bladder into a stringer preform; disposing the bladder and the stringer preform between the caul plate and the mandrel; two-stage indexing comprising indexing the caul plate to the mandrel to provide initial indexing and indexing an inflation port of the bladder to an opening of the caul plate to provide for fine indexing; pushing the caul plate toward the preform, the stringer preform, and the mandrel; hardening the preform and the stringer preform into a composite part while the caul plate is held against the preform; separating the caul plate from the composite part; cleaning the caul plate at a cleaning station outside of the clean room environment; and returning the caul plate to the clean room environment where it may be re-used with the mandrel for hardening of a second preform. ### Claim 2 (depends on 1) The method of claim 1 comprising: evacuating air within a sealed chamber bound by the caul plate, the first circumferential seal, and the mandrel, to allow atmospheric pressure to push the caul plate towards the preform, the stringer preform, and the mandrel. ### Claim 3 (depends on 2) The method of claim 2 further comprising: sealing an elastomeric flap to the mandrel, wherein the elastomeric flap extends from the caul plate and wherein the first circumferential seal is disposed between the flap and the sealed chamber. ### Claim 4 (depends on 2) The method of claim 2 further comprising: inserting the bladder into the stringer preform prior to covering the preform with the caul plate. ### Claim 5 (depends on 4) The method of claim 4 further comprising: sealing the caul plate to the bladder; and inflating the bladder. ### Claim 6 (depends on 5) The method of claim 5 further comprising: inflating the bladder by opening the bladder interior to atmospheric pressure when the sealed chamber is evacuated. ### Claim 7 (depends on 6) The method of claim 6 further comprising: pressurizing and shaping the stringer preform with bladder inflation. ### Claim 8 (depends on 5) The method of claim 5 wherein: sealing the caul plate to the bladder is performed by screwing a banjo bolt into the inflation port. ### Claim 9 (depends on 4) The method of claim 4 wherein: the caul plate consolidates the stringer preform against the mandrel. ### Claim 10 (depends on 1) The method of claim 1 wherein indexing the caul plate to the mandrel comprises aligning an indexing feature of the caul plate with an indexing feature of the mandrel. ### Claim 11 (depends on 1) The method of claim 1, further comprising: transporting the caul plate with a strongback and wherein indexing the caul plate to the mandrel comprises aligning an indexing feature at the strongback with an indexing feature at the mandrel. ### Claim 12 (depends on 1) The method of claim 1 wherein vacuum sealing the caul plate to the mandrel further comprises: vacuum sealing the caul plate to the mandrel via a second circumferential seal disposed entirely within the first circumferential seal. ### Claim 13 (depends on 12) The method of claim 12 wherein vacuum sealing the caul plate to the mandrel further comprises: vacuum sealing the caul plate to the mandrel via a third circumferential seal disposed entirely within the second circumferential seal. ### Claim 14 (depends on 13) The method of claim 13 further comprising: subdividing a volume between the first circumferential seal and the second circumferential seal into quadrants. ### Claim 15 (depends on 13) The method of claim 13 further comprising: slipping the mandrel relative to caul plate at one of the first, second, or third circumferential seals. ### Claim 16 (depends on 1) The method of claim 1 wherein: the caul plate forms an Outer Mold Line (OML) and the mandrel forms an Inner Mold Line (IML) for a section of fuselage. ### Claim 17 (depends on 16) The method of claim 16 wherein: the section of fuselage is a half barrel section. ### Claim 18 (depends on 16) The method of claim 16 wherein: the section of fuselage is a full barrel section. ### Claim 19 (depends on 1) The method of claim 1 wherein: the caul plate forms an Inner Mold Line (IML) and the mandrel forms an Outer Mold Line (OML) for a section of fuselage. ### Claim 20 (depends on 1) The method of claim 1 wherein: the mandrel further comprises a vacuum system that controllably applies a vacuum via vacuum holes at the mandrel. ### Claim 21 (depends on 1) The method of claim 1 wherein: the caul plate further comprises a vacuum system that controllably applies a vacuum via vacuum holes at the caul plate. ### Claim 22 (depends on 1) The method of claim 1 wherein: the inflation port of the bladder is fastened through the opening in the caul plate. ### Claim 23 (depends on 1) The method of claim 1 wherein: the channel formed in the mandrel has a half-circle cross-section. ### Claim 24 (depends on 1) The method of claim 1 wherein: the caul plate forms a half barrel shape of half barrel sections for a section of fuselage.