HEATING ELEMENTS FOR REPAIR OF MOLDING DEFECTS FOR CARBON FIBER THERMOPLASTIC COMPOSITES

• US 20180361690A1
• Filed: 06/15/2017
• Published: 12/20/2018
• Est. Priority Date: 06/15/2017
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Huang, Xiaosong, Kia, Hamid G.
• Granted Patent: US 10,611,104 B2
• Time in Patent Office: Days
• CPC Class Codes: B29C 2035/0811 using induction
• CPC Class Codes: B29C 43/18 incorporating preformed parts or layers, e.g. compression moulding around inserts or for coating articles B29C43/206 takes precedence
• CPC Class Codes: B29C 43/222 characterised by the shape of the surface
• CPC Class Codes: B29C 43/32 Component parts, details or accessories; Auxiliary operations
• CPC Class Codes: B29C 43/52 Heating or cooling
• CPC Class Codes: B29C 65/22 Heated wire resistive ribbon, resistive band or resistive strip electrical insulating support therefor B29C66/81871
• CPC Class Codes: B29C 65/70 by moulding using a particular moulding technique, see the relevant technique , e.g. by injection B29C45/14467
• CPC Class Codes: B29C 66/301 Three-dimensional joints, i.e. the joined area being substantially non-flat B29C66/5223, B29C66/5224, B29C66/5225 take precedence
• CPC Class Codes: B29C 66/721 Fibre-reinforced materials B29C66/729 takes precedence
• CPC Class Codes: B29C 66/73921 characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/8122 characterised by the composition of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
• CPC Class Codes: B29C 66/81262 Electrical and dielectric properties, e.g. electrical conductivity
• CPC Class Codes: B29C 73/12 Apparatus therefor, e.g. for applying B29C73/30 takes precedence
• CPC Class Codes: B29C 73/30 for local pressing or local heating
• CPC Class Codes: B29C 73/34 for local heating
• CPC Class Codes: B29K 2105/06 containing reinforcements, fillers or inserts
• CPC Class Codes: B29K 2883/00 Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as mould material
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer

Abstract

Methods of repairing a manufacturing defect in a molded polymeric composite structure are provided. A polymeric patch may optionally be disposed over a defect on a first contoured surface of the molded polymeric composite structure having the defect. A heating element that defines a second contoured surface complementary with at least a portion of the first contoured surface is applied over the polymeric patch. The heating element includes an electrically conductive layer that includes a fabric and a thermoset polymer. The polymeric patch is heated with the heating element, where the heating element has a substantially uniform temperature across the second contoured surface so that the polymeric patch fills the defect. Methods of making the customized heating elements and the customized heating elements are also provided.

Claims

1. A method of repairing a manufacturing defect in a molded polymeric composite structure, the method comprising:

applying a heating element over a first contoured surface of the molded polymeric composite structure comprising a defect, wherein the heating element defines a second contoured surface complementary with at least a portion of a first contoured surface and the heating element comprises an electrically conductive layer including a fabric and a thermoset polymer; and

heating a portion of the first contoured surface with the heating element, wherein the heating element has a substantially uniform temperature across the second contoured surface to repair the defect.

2. The method of claim 1, further comprising disposing a polymeric patch over the defect on the first contoured surface of the molded polymeric composite structure prior to the applying.

3. The method of claim 2, wherein the molded polymeric composite structure comprises a thermoplastic polymer and a reinforcement material and the polymeric patch is a polymeric composite also comprising the thermoplastic polymer and the reinforcement material.

4. The method of claim 2, wherein the polymeric patch comprises a polymeric composite having the same polymeric matrix as the polymeric composite structure and optionally the same reinforcing material as the polymeric composite structure.

5. The method of claim 2, wherein the heating of the polymeric patch with the heating element is to a maximum temperature that is less than or equal to about 50°

C. above a melting point of the polymeric composite structure.

6. The method of claim 2, wherein the polymeric patch and the molded polymeric composite structure each comprise a thermoplastic polymer individually selected from the group consisting of:

polyamides, polyester, polyolefin, polyurethane, poly(acrylic acid), poly(methyl acrylate), poly(methyl methacrylate), acrylonitrile butadiene styrene, polybenzimidazole, polylactic acid, polycarbonate, polyether sulfone, polyetherether ketone, polyetherimide, polyethylene, polyphenylene oxide, polyphenylene sulfide, polypropylene, polystyrene, polyvinyl chloride, polytetrafluoroethylene, and co-polymers and combinations thereof, and the molded polymeric composite structure further comprises a reinforcement material selected from the group consisting of;

carbon fibers, glass fibers, basalt fibers, aramid fibers, boron fibers, ceramic fibers, polyester fibers, ultra-high molecular weight polyethylene fibers, hemp fibers, and combinations thereof.

7. The method of claim 1, wherein the temperature across the second contoured surface varies less than or equal to about 15°

C.

8. The method of claim 1, wherein the second contoured surface has a textured surface that corresponds to a texture of the first contoured surface.

9. The method of claim 1, wherein the heating element further comprises a pair of terminal connected to an external power source, so that the heating is a resistive heating process.

10. The method of claim 1, wherein the heating element is part of an assembly comprising an induction heater, so that the heating is an inductive heating process.

11. The method of claim 1, further comprising compression molding a composite blank to form the molded polymeric composite structure having the defect prior to the applying.

12. A heating element for repairing a defect in a molded polymeric composite structure, the heating element comprising an electrically conductive layer including a fabric and a thermoset polymer, wherein the electrically conductive layer defines a contoured surface complementary with at least a portion of a corresponding surface of the molded polymeric composite structure comprising the defect and the heating element is capable of maintaining a substantially uniform temperature across the contoured surface.

13. The heating element of claim 12, wherein the fabric is an electrically conductive fabric comprising a woven carbon fiber fabric or a resistance wire fabric.

14. The heating element of claim 12, wherein the contoured surface defines a textured surface.

15. The heating element of claim 12, further comprising a pair of terminals in electrical communication with the electrically conductive layer.

16. The heating element of claim 12, wherein the thermoset polymer comprises a siloxane elastomer.

17. The heating element of claim 16, wherein the electrically conductive layer comprises an electrically conductive composite comprising the siloxane elastomer and an electrically conductive filler distributed therein.

18. A method of forming a heating element for repairing a manufacturing defect in a molded polymeric composite structure, the method comprising:

disposing a fabric in a cavity of a template defining a contoured surface profile;

introducing a liquid precursor of thermoset polymer into the cavity so that the liquid precursor fills the fabric, wherein at least one of the liquid precursor or the fabric comprises an electrically conductive material; and

solidifying the liquid precursor to form the thermoset polymer, wherein the thermoset polymer and the fabric together define the heating element having the contoured surface profile.

19. The method of claim 18, wherein the fabric is an electrically conductive fabric comprising a woven carbon fiber fabric and the thermoset polymer comprises a siloxane elastomer.

20. The method of claim 19, wherein the liquid precursor further comprises an electrically conductive filler and after the solidifying, an electrically conductive composite is formed comprising the siloxane elastomer and the electrically conductive filler.