Method and apparatus for forming a hollow FRP article by internal pressure molding
A method for forming a hollow FRP article by internal pressure molding includes positioning a FRP prepreg on a periphery of an airtight internal-pressure holding tube, inserting a composite body including the internal-pressure holding tube and the prepreg into a vacuum chamber containing a forming die, evacuating the vacuum chamber in an isolation state where the composite body and the forming die do not contact each other, and clamping the forming die to bring the forming die and the composite body into contact with each other and heating the forming die with an application of pressure to an inside of the internal-pressure holding tube after completion of the evacuating step.
1. A method for forming a hollow FRP article by internal pressure molding, comprising:
positioning a FRP prepreg on a periphery of an airtight internal-pressure holding tube;
inserting a composite body including said internal-pressure holding tube and said prepreg into a vacuum chamber containing a forming die and a composite body support device, said composite body support device having an anti-deflection support base and a cantilever support base provided with a front support portion and a rear support portion;
positioning said composite body on said composite body support device such that said composite body is supported in cantilever fashion by said cantilever support base and is prevented from developing deflections by said anti-deflection support base;
evacuating said vacuum chamber in an isolation state where said composite body and said forming die do not contact each other, so that air having existed in a space between an outer periphery of said composite body and a periphery of said forming die is removed; and
clamping said forming die to bring said forming die and said composite body into contact with each other and heating said forming die with an application of pressure to an inside of said internal-pressure holding tube after completion of said evacuating step, while maintaining said evacuation state, where air having existed in a space between said outer periphery of said composite body and said periphery of said forming die has been removed.
2. The FRP hollow article forming method according to claim 1 , wherein said prepreg positioning step comprises:
covering a mandrel with said internal pressure holding tube; and
wrapping said FRP prepreg around said periphery of said internal-pressure holding tube.
3. The FRP hollow article forming method according to claim 2 , wherein said clamping and heating step comprises applying pressure to said inside of said internal-pressure holding tube through air passages formed on said mandrel.
4. The FRP hollow article forming method according to claim 1 , wherein said prepreg positioning step comprises:
covering a mandrel with said internal-pressure holding tube;
wrapping said FRP prepreg around said periphery of said internal-pressure holding tube; and
removing said mandrel after said wrapping step.
5. The FRP hollow article forming method according to claim 4 , wherein said clamping and heating step comprises applying pressure to said inside of said internal-pressure holding tube through an air-injecting mouth piece fixed to an open end of said internal-pressure holding tube after said mandrel is removed.