Design and Control of the pneumatic system for a automatic metal classification

Abstract

South Korea is a resource-dependent country that relies on the import of most metal resources. Therefore, we should save resources through recycling. In particular, the recycle rate of non-ferrous metals is very low. This is due to the limitations of the recycling technology currently in use. To overcome these limitations, non-ferrous metal recycling studies using laser induced breakdown spectroscopy are underway. In this paper, we will discuss a automatic metal classification system that receives metal information from a laser-induced breakdown spectrum and classifies a metal scrap by type. Currently, sorting system use non-contact pneumatic system. Compared to the contact method, the system is durable and can be controlled at high-speed. We will study how to effectively use the flow rate by modeling the pneumatic system. However, when using simple pneumatic system, sorting of metal scraps by type has limitation. The reason is that the same flow rate is injected. In other words, it is difficult to sort the same location if the metal scraps of the same kind with different masses are putted.This has a great impact on the sorting accuracy and the recycling throughput of metal scraps. In this paper, the most efficient method of flow rate control is proposed. The proposed method is more advantageous in terms of economics, structure, and bandwidth than conventional methods such as Servo valve or E/P regulator. Therefore, the pneumatic system for the proposed method is designed and controlled to sort the metal by type regardless of its weight.