Research On Design Methods Of Active Disassembly Structure Triggered By Temperature

The application objects of active disassembly using smart materials (ADSM) mainlycomprise cellphones, automobiles, liquid crystal displays (LCDs), printed circuit boards(PCBs), hard disk drives (HDDs), buttons and variety of threaded parts and fastening parts.There are two mainly problems using ADSM methods.(1) The trigger ways are mainly thetraditional ways such as water-bath heating and air bath heating. Products need to beintegrally heated using these ways, thus causing long and uncontrollable heating time andhigh consumption of energy, so some parts which have bad thermal resistance will begravely damaged. Especially, in multi-step active disassembly methods of electronicproducts, the active disassembly effect is far from satisfactory using traditional trigger ways.It costs long time to heat the inner active disassembly structures, which will bring about thelong trigger time and low disassembly efficiency.(2) Active disassembly structures needtwo molding steps. In the second molding step shaped material is forced to the connectionstate by mold pressing to enable parts and components assembly. Because accuracy controlof mold pressing is lower than that of injection, the second molding step increases costs forimproving assembly accuracy, usually accounting for80%of the total cost and, in addition,the machining processes are complex.Active disassembly method triggered by electric heat belongs to the local heat trigger,whose heating time is short and controllable and the heat energy is concentrated. So theenergy cost is low, the fire damage to other parts and components is also low. Differentfrom the trigger intensity gradient increasing way of normal active disassembly methods,the disassembly time of active disassembly method triggered by electric heat can becontrolled by adjusting the power of heating element, thus achieving the multi-step activedisassembly of electronic products and improving the disassembly efficiency. Researchingdesign methods of active disassembly structure triggered by electric heat and multi-stepactive disassembly of products has instructive significance for enriching and improvingactive disassembly theories using such method. Decapitated head method belongs to localdamaged disassembly methods. There is no need for a second molding step in activedisassembly structures based on the decapitated head method. The machining processes are simpler and the manufacturing cost is lower than the method requiring two molding steps,while the disassembly efficiency is much higher. It is important for reducing manufacturingcost and improving disassembly efficiency to research the design methods of activedisassembly structures based on the decapitated head method. It will lay the foundation forenriching and improving theory systems of ADSM and applying active disassemblytechnology to industrial practice to research design methods of active disassembly structuretriggered by electric heat and design methods of active disassembly structures based on thedecapitated head method and to form design method systems of active disassemblystructure triggered by temperature.