Haihong Huang

Study on Disassembling Approaches of Electronic Components Mounted on PCBs

With the rapid development of modern industry, more and more electronic and electric products containing Printed Circuit Boards (PCBs) are produced, consumed, and discarded in our daily life. The disassembling and reuse of electronic components mounted on these discarded PCBs are meaningful to reuse the valuable electronic components, reduce the pollution to the environment, reuse the bare PCBs, and retrieve the materials of PCBs. Four evaluation principles of disassembling methods, components reutilization rate, reliability and uniformity, thermal energy consumption and environmental impact, are analyzed. Based on the analysis of the existing disassembling approach, a new method is presented, which adopts a kind of special liquor, methylphenyl silicone oil, as the medium to transmit heat to the PCBs. The ultrasonic is used in the liquor to accelerate the melting and dropping of soldering tin through ultrasonic vibrations. An experimental framework has been established. The experiment proves that the method has good performances such as high efficiency of energy utilization and high unsoldering proportion.

An Energy-Saving Method by Balancing the Load of Operations for Hydraulic Press

Large energy loss caused by mismatching between the installed power and demanded power, as well as the wasted potential energy, is a serious problem for a hydraulic press. In order to reduce the energy loss, an energy-saving method by balancing the load of operations of presses was proposed based on the analysis of energy flow characteristics of the hydraulic system. In the method, the motor pumps in the drive system are shared in different time by a unit composed of two hydraulic presses so that the energy loss caused by unloading operations can be reduced. Furthermore, these two presses are combined, and the excessive energy from one press can serve as the input energy to the other one during some operations to improve the energy efficiency of the drive system, and the potential energy can be utilized directly. Meanwhile, operation durations of these combined presses are optimized for coordination of working processes. The method was applied to two hydraulic presses in a tandem line, and the energy consumption was obtained by quantifying the characteristics of conversion components. Results indicate that for a single press, 36% of electrical energy can be saved in the investigated forming processes.

Magnetic memory signals of ferromagnetic weldment induced by dynamic bending load

Abstract Metal magnetic memory testing is a novel method for evaluating the fatigue damage of ferromagnetic weldments. To promote a further understanding of the impact of fatigue loads on magnetic memory signals of weldments, the normal component of magnetic signals, Hp(y), on the centre-notched welding specimens were measured during dynamic bending fatigue tests. The variation of peaks–troughs differential value ΔHp(y) of magnetic signals and its maximum gradient Kmax at the welded joint were also investigated. Results indicated that the ΔHp(y) on scanning line near the notch increased sharply when stress concentration and crack initiation appeared in the specimens. The microstructures on scanning lines were also examined. It shows that there was an increase in intragranular slips with the increase in loading cycles, and the change in crystallographic textures and movement of dislocations contributed to the magnetic signals varying significantly. The maximum gradient Kmax was found to increase exponentially with the increase in crack length, which is well coincident with the analytic result of the magnetic dipole model. The research provides a potential possibility of quantitative evaluation on stress concentration and crack in weldments under dynamic bending loads.

Research on Design for Environment Method in Mass Customization

With the productive mode changes from mass production to mass customization, the design for environment (DFE) method has to be adapted to it. The purpose of this study is to realize green design in mass customization mode. In this study, the process of the DFE method in MC mode is systematically discussed, then a concept of green product information model is proposed to support the design process. A product configurator for DFE is presented in detail, at last a green design of refrigerator was used as exemplification of the method.

Semi-quantitative method for task planning in product eco-design

Ensuring the environmental sustainability of products is challenging because it involves all the stages and processes throughout product life cycle. Product eco-design is essential to achieve it. In the proposed methodology, product eco-design is implemented based on five eco-design elements, namely, function, material, geometric structure, connection relationship and manufacturing process. However, because of the fragmentation of existing eco-design tools, the gap between eco-design evaluation and eco-design optimisation requires a new mechanism to seamlessly integrate them for efficient industrial applications. A new checklist tool called Checklist of Product Eco-design Optimisation Potential (CPEOP) is developed to assess product eco-design optimisation potential. Based on the new tool, optimisation effect of product eco-design can be quantitatively assessed. Furthermore, a novel semi-quantitative method for task planning in product eco-design is proposed, which involves evaluating the product with CPEOP, screening candidates for eco-design and determining the candidates’ optimisation directions. The uncertainties arising from CPEOP and enterprise design status quo are further analysed. Subsequently, a case study on a refrigerator is conducted to elucidate the process of the method and reveal its potential. The proposed method is then discussed through a comparison with two mainstream eco-design tools.

Product Disassembly Model Based on hierarchy network graph

Disassembly is the precondition of recycling products. And product disassembly model is the basis for product disassembly analysis. A product disassembly model named hierarchy network graph model is introduced. To describe the relation between parts, the model adopts network graph model, in which the nodes describe the parts information and the edges describe the constraints information between parts. To describe the product assembly hierarchy relation, the model adopts the hierarchy model. At the same time, the dynamic transfer mechanism is adopted to satisfy the different disassembly goals.