PSI - Issue 33

Nassima Naboulsi et al. / Procedia Structural Integrity 33 (2021) 989–995 Nassima Naboulsi et al. / Structural Integrity Procedia 00 (2019) 000–000

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1. Introduction The number of 3D printer users continues to grow, and between failed print waste and print media waste, plastic recycling is emerging as an absolute necessity (Zhong & Pearce, 2018) . 3D printing technologies are widely used for the production of polymer components using fused deposition modeling (FDM) (Mwema & Akinlabi, 2020) . This process allows to form a 3D print by depositing successive layers of extruded thermoplastic filament (Carneiro et al., 2015). This is why we had the idea of designing a pilot-scale extruder to ensure the immediate availability of filament spools to produce experimental specimens for our research and to satisfy the laboratory's equipment needs and to free ourselves from the constraints related to the purchase of filament spools. In this context, various studies have been conducted to satisfy this need (Nassar et al., 2019) (Nithya Priya et al., 2021). In fact, the effect of temperature control of the heating system on the plastic pellets during the filament production cycle is very important to maintain the reliability and conformity of the filaments to ensure that the raw material is melted at a precisely controlled temperature to extract good quality filaments. In this paper, the temperature control is achieved using a proportional-integral-derivative (PID) controller (Ang et al., 2005). Therefore, temperature control must be performed in such a way that the static error tends to zero and to have a system that responds as quickly as possible with the least amount of overshoot. In this paper, we have identified and modeled the process of the extruder heating system that describes the most representative behavior of the process in the form of a transfer function using the classical Broïda method (Ribeiro et al., 2017). Then we have controlled the control loop by choosing the structure of the controller the most adapted to the heating system and by calculating the parameters of this controller (Septiani et al., 2017) (Dehghani & Khodadadi, 2017) (Oo et al., 2018) in order to meet the greatest number of required constraints. The different simulations will be established in the form of block diagrams using the SIMULINK software. And finally, by choosing the actions (P, I and D) of the controller and by tuning the values to be applied to the parameters (kp, Ti and Td), we were able to obtain the most comfortable response to the specifications.

Nomenclature K p

is the proportional gain is the integral gain is the derivative gain

K I K D T I T D

is the integral time constant is the derivative time constant

K

is the Static gain

τ

is the delay

T

is the time constant

2. Methods and Materials The extruder of plastic filaments, as shown in Fig. 1, consists of a worm screw which turns inside a cylindrical barrel. The screw allows to transmit the material to be extruded, often thermoplastic in the form of pellets or plastic waste which are initially introduced in a hopper located at the end of the machine towards the head of the extruder which is composed of another copper tube in the form of a chamber in which the material is collected and melted in temperature by a heating system in order to pass in the nozzle to give the final form of the filament. The extruder has two main functions: The first is to transport the material to be extruded and the second is to melt the material from a temperature control process is performed by the controller PID which constitute three different control factors; Proportional, Integral and Derivative; the Fig. 2 illustrates the block diagram of the extruder's thermal control system.