Tooling and process for variability reduction of composite structures

• US 5,292,475 A
• Filed: 03/06/1992
• Issued: 03/08/1994
• Est. Priority Date: 03/06/1992
• Status: Expired due to Fees

• Current Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Inventors: Mead, William T., Clayton, Colin G.
• Primary Examiner(s): Woo, Jay H.
• Assistant Examiner(s): SMITH, DUANE
• Application Number:
  US07/847,519
• Time in Patent Office: 732 Days
• Field of Search: 264/257, 264/258, 264/313, 264/314, 264/510, 264/511, 264/512, 264/546, 264/316
• US Class Current: 264/257
• CPC Class Codes: B29C 2791/001 Shaping in several steps
• CPC Class Codes: B29C 37/005 Compensating volume or shape change during moulding, in general
• CPC Class Codes: B29C 43/14 in several steps
• CPC Class Codes: B29C 43/36 Moulds for making articles of definite length, i.e. discrete articles
• CPC Class Codes: B29C 70/46 using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
• CPC Class Codes: B29D 99/0003 Producing profiled members, e.g. beams
• CPC Class Codes: B29L 2031/003 having a profiled transverse cross-section

Abstract

Variability between composite structures can be reduced by utilizing forming and curing tooling that includes a cure tool and a preform tool. The cure tool has a curing surface. The curing surface defines the shape of a cured composite structure. The preform tool has a preform surface that is divided into at least first and second surface area portions. The first surface area portion is of the same surface shape to the corresponding surface area of the curing surface on the cure tool. The second surface portion is of a surface shape that is different from the surface shape of the corresponding surface area of the curing surface on the cure tool. The differences between the second surface area portion of the preform surface and its complementary surface on the curing surface is such that there is an increase in the surface area of the second surface area portion of the preform surface compared to a corresponding area on the curing surface of the cure tool. Because of these differences, when a preform structure is formed on the preform tool, additional uncured preform material is located at the area defined by the second surface area of the preform tool. Upon curing of the preform structure in the cure tool, this additional material is transferred to adjacent radii resulting in reduction of porosity, bridging, excess resin richness and delamination at the radii.

Claims

1. A method of manufacturing a structural composite layup from a laminate of uncured layers of resin impregnated continuous fiber reinforced composite material in the shape of a mandrel a portion of which has an inside radius of curvature, comprising:

shaping said laminate around a tool having a portion with an outside radius of curvature conforming, when taken with the laminate, generally to that of said inside radius portion of said mandrel to form a shaped layup,

providing on said tool, adjacent said outside radius of curvature, a deformation about which said laminate further extends to provide an additional bulk of laminate positioned to lie adjacent said inside radius and adequate to allow slippage between laminate layers when said shaped layup is later molded onto said mandrel,

placing the shaped layup into said mandrel,

thereafter applying pressure to said layup to press the layup into conformance with said mandrel and said inside radius of curvature therein,

the excess material in said deformation allowing slippage between the laminate layers so that said additional bulk thereat moves into close conformance with said radius of inside curvature to form a consolidated composite closely conforming to said mandrel and its inside radius of curvature free of defects.