Composite lamination method

• US 4,065,340 A
• Filed: 04/28/1977
• Issued: 12/27/1977
• Est. Priority Date: 04/28/1977
• Status: Expired due to Term

• Current Assignee: The United States Of America As Represented By The National Aeronautics And Space Administration
• Original Assignee: The United States Of America As Represented By The National Aeronautics And Space Administration
• Inventors: Dickerson, George E.
• Primary Examiner(s): Powell, William A.
• Assistant Examiner(s): Massie, Jerome W.
• Application Number:
  US05/792,067
• Time in Patent Office: 243 Days
• Field of Search: 156/161, 156/219, 156/285, 156/286, 156/311, 156/312, 156/313, 156/288, 156/264, 156/154, 156/289, 156/153, 156/299, 156/300, 156/306, 264/135, 264/137, 264/259, 264/261, 264/263, 264/264, 264/90, 264/157, 428/290, 428/295, 428/294, 428/301, 428/302
• US Class Current: 156/154
• CPC Class Codes: B29C 2043/3644 Vacuum bags; Details thereof, e.g. fixing or clamping
• CPC Class Codes: B29C 2791/001 Shaping in several steps
• CPC Class Codes: B29C 2793/009 after shaping
• CPC Class Codes: B29C 35/02 Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mouldcold vulcanisation B29C35/18 ; vulcanising tyres, presses therefor B29D30/0601
• CPC Class Codes: B29C 43/12 using bags surrounding the moulding material or using membranes contacting the moulding material
• CPC Class Codes: B29C 70/342 using isostatic pressure
• CPC Class Codes: B29C 70/44 using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding
• CPC Class Codes: B29C 70/545 Perforating, cutting or machining during or after moulding
• CPC Class Codes: B29C 70/549 Details of caul plates, e.g. materials or shape
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2105/24 crosslinked or vulcanised
• CPC Class Codes: B29K 2105/243 Partially cured
• CPC Class Codes: B29K 2307/00 Use of elements other than metals as reinforcement
• CPC Class Codes: B32B 2038/0076 Curing, vulcanising, cross-linking
• CPC Class Codes: B32B 2260/021 Fibrous or filamentary layer layers of natural mineral fibres or particles being impregnated in a plastic substance B32B19/02
• CPC Class Codes: B32B 2260/046 Synthetic resin
• CPC Class Codes: B32B 2305/076 Prepregs
• CPC Class Codes: B32B 2309/02 Temperature
• CPC Class Codes: B32B 2309/12 Pressure
• CPC Class Codes: B32B 37/1018 using only vacuum
• CPC Class Codes: B32B 38/0004 : Cutting, tearing or severing, e.g. bursting; Cutter details cutting in general B26D; laminating combined with punching or perforating B32B38/04; removing all or part of the layers B32B38/10; cutting in combination with laying up and registration B32B38/185 takes precedence
• CPC Class Codes: B32B 5/26 : another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: Y10T 156/1075 : of plural laminae from single stock and assembling to each other or to additional lamina
• CPC Class Codes: Y10T 156/1093 : with covering of discrete laminae with additional lamina
• CPC Class Codes: Y10T 428/249941 : Fiber is on the surface of a polymeric matrix having no embedded portion

Abstract

A process for preparing relatively thick composite laminate structures wherein thin layers of prepreg tapes are assembled, these thin layers are cut into strips that are partially cured, stacked into the desired thickness with uncured prepreg disposed between each layer of strips and the thus formed laminate finally cured and thereafter machined to the desired final dimensions.

Claims

1. A process of preparing structural components of composite laminates comprising:

providing prepreg resin impregnated fiber tape material having the fibers therein running the length of the tape,

cutting the prepreg tape into a plurality of desired lengths,

stacking the plurality of lengths of tape in layers to a predetermined thickness while maintaining the same fiber orientation for each layer,

partially curing the stacked tape assembly into a unitary mass under vacuum for approximately ten minutes and at an elevated temperature of at least 350°

F.,

cooling the partial cured mass and cutting it into a plurality of strips along the parallel orientation of the fibers,

stacking this plurality of strips vertically in layers atop each other with two strips of uncured prepreg tape disposed between each of the plurality of laminate strips,

curing the stacked layer strips into a unitary structure under vacuum, pressure and an elevated temperature of at least 350°

F. for least thirty minutes,

cooling the cured structure to a minimum of 150°

F. while maintaining the pressure and vacuum, and after allowing to cool to room temperature,

machining the unitary structure formed into the final desired size and shape.

2. The method of claim 1 wherein the step of partially curing the stacked tape assembly into a unitary mass includes, placing the stacked assembly between separator cloths and fiberglass bleeder cloths, bagging the resulting stack assembly in a vacuum bag, and placing the bagged assembly in a pressure vessel.

3. The method of claim 2 wherein the bagged stack assembly in the pressure vessel is heated from room temperature to 350°

F. in increments of 2°

-3°

F. per minute after the assembly is placed under full vacuum.

4. The method of claim 3 wherein a pressure of 85 psi external pressure is applied and maintained to the assembly when the temperature thereof reaches 225°

F.

5. The method of claim 4 wherein the vacuum and external pressure are maintained until the temperature reaches and is maintained at about 350°

F. for approximately ten minutes.

6. The method of claim 5 wherein the vacuum and external pressure are maintained while permitting the assembly to cool to at least 150°

F. prior to removal of the assembly from the pressure vessel.

7. The method of claim 1 wherein the plurality of partially cured strips are stacked so as to maintain the fiber orientation of each layer in the stack parallel to that of the adjacent layer.

8. The method of claim 1 wherein the plurality of partially cured strips are stacked in layers so as to maintain the fiber orientation of each layer in the stack perpendicular to that of the adjacent layer.

9. The method of claim 1 wherein the plurality of partially cured strips are stacked in layers so as to maintain the fiber orientation of each layer in the stack at an angular relationship to that of the adjacent layer in the range of 1°

to 179°

.

10. The method of claim 1 wherein the fiber orientation of the strips of uncured prepreg tape between each layer in the stack is disposed parallel with the fiber orientation of the adjacent layer of the stack.

11. A process of preparing structural components of composite laminates and skin covers therefor comprising:

providing prepreg resin impregnated fiber tape material having the fibers therein running the length of the tape,

12. cutting the prepreg tape into a plurality of desired lengths,

stacking the plurality of lengths of tape in layers to a predetermined thickness while maintaining the same fiber orientation for each layer,

partially curing the stacked tape assembly into a unitary mass under vacuum and at an elevated temperature of at least 350°

,

cooling the partially cured mass and machining it into the desired configuration,

preparing a partially cured prepreg skin cover for the machined configuration from layers of prepreg tape by the same process,

positioning this partially cured skin onto the machined configuration so as to maintain parallel fiber orientation between the configuration and skin and with two strips of uncured prepreg tape disposed between the configuration and skin and having the fibers therein disposed parallel to the fibers in the configuration and skin,

curing the stacked configuration and skin into a unitary structure under vacuum, pressure and an elevated temperature of at least 350°

F. for at least thirty minutes, and

maintaining the pressure while cooling the cured structure to a minimum of 150°

F. while maintaining the pressure and vacuum.