Development of molding method of carbon fiber reinforced thermoplastics by using direct resistance heating and induction heating

For the applications of CFRTP to car components in the automotive industry, it is necessary to reduce the cost of the molding process. Recently, a heating method of the mold by using high frequency direct resistance heating, which heats only the mold surface by joule heating is attracting a great deal of attention, as it enables fast mold heating for cost reduction. When the high frequency alternative current is applied to the upper and lower molds in the same direction, however, the temperature of the press surface of the mold is inefficiently heated due to the attenuation of magnetic field. Furthermore, although the CFRTP molding method using the proximity effect was developed, in which the high frequency alternative current is applied to the upper and lower molds in the opposite direction, electric short circuit of the molds by current difference is one of the issues to be solved. In this study, the CFRTP molding method was developed by applying alternating current to only the lower mold in which the lower mold was heated with direct resistance heating and the upper mold and carbon fiber fabric were heated by induction heating. One pair of rectangular solids was used as the simplest mold system and FEM analysis of the electromagnetic field and heat transfer were compared with the experimental results. The upper mold and carbon fiber fabric were successfully heated by induction heating from the applied alternating current to the lower mold. The mold was efficiently heated by reducing the thickness and using materials with relatively higher magnetic permeability. © 2019 The Society of Materials Science, Japan.