US Patent 7204286 Apparatus for continuously forming FRP square pipe

An apparatus 1 for continuously forming an FRP square pipe comprises a long core 10 for laminating prepreg sheets, and to this core 10 are fed prepreg sheets from prepreg laminating devices 20, 30, 40 and 50 with a release film interposed between the core, so as to be laminated into square pipe form. The core 10 has an outer diameter size smaller than the inner diameter size of the square pipe to be formed. The outer circumference of the square pipe is wrapped with a tape-like film fed from a tape-like release film wrapping device 200 in spiral fashion, and the work is heated and pressed in a hot press 100. The work is then subjected to additional heating in a postcure furnace 110 to form the FRP square pipe. The square pipe is intermittently pulled by a puller 130 disposed downstream of a clamp 120. The pipe is then cut to predetermined lengths by a cutter not shown to be completed as a product.