Local heat clamp bending of carbon fiber-reinforced thermoplastic sheet
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ORIGINAL ARTICLE
Local heat clamp bending of carbon fiber-reinforced thermoplastic sheet Daichi Tatsuno 1
&
Takeshi Yoneyama 1 & Takahito Matsumoto 1
Received: 30 April 2020 / Accepted: 5 October 2020 / Published online: 14 October 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract Local heat clamp bending equipment for carbon fiber-reinforced thermoplastic (CFRTP) sheets has been developed. The equipment holds a CFRTP sheet with thin metal foils to heat the bending region to the resign melting temperature and then bends the sheet keeping the hold by the foils under continuous pressure application during cooling. Using this equipment, it has been revealed that even a unidirectional continuous carbon fiber sheet can be locally bent by the in-plane wavy deformation of the fiber in the inner plies, while keeping the same profile length of the outside ply. In contrast, in the bending of unidirectional carbon fiber sheets with cutting at constant length, a combination of the wavy deformation of the inside ply and expansion of the outside ply has been observed. The developed bending equipment will be useful for the bending of CFRTP sheets similar to how a press brake is used for sheet metal forming. The development of the local heat clamp bending equipment will expand a field of bending for mass production using CFRTP sheets. Keywords Carbon fiber-reinforced thermoplastic . Bending . Thermoforming . Carbon fiber-reinforced plastic
1 Introduction In the field of sheet metal forming, bending is a popular method for making various metal boxes or other similar parts. For this purpose, the so-called press brake is widely used. Considering that the carbon fiber-reinforced thermoplastic (CFRTP) sheet is widely used, the bending technique for CFRTP sheet must be useful in making various parts of CFRTP. However, it is thought that laminated plates must be entirely heated for bending to be able to slip the plies, as shown in Fig. 1a. It is true because carbon fiber cannot plastically extend or contract, i.e., each ply bends with each bending radius and a slip occurs between the laminated plies. The slip occurs both in the bending region and in the outside region all over the sheet boundary. Previously, interest on the bending of the laminate of CFRTP sheets was focused on elastic deformation after the bending and slip between the plies. Spring-in phenomenon has been investigated by
* Daichi Tatsuno [email protected] 1
Advanced Manufacturing Technology Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
Zahlan and O’Neill [1], Hou and Friedrich [2], Hou et al. [3], Salomi et al. [4], Padovec et al. [5], and Konda et al. [6]. Usually, if the laminated continuous fiber-reinforced plastic sheet is partially heated and bent, out-of-plane wrinkling fibers manifest at the surface of the inside corner. Bruns and Raatz [7] developed equipment that grasps the sheet and partially heats using a vortex nozzle with hot air. They applied it for right-angle bending and pointed out the oc
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