دانلود رایگان مقاله انگلیسی طراحی لایه های سرمایش ساختاری برای تجهیز تولید افزودنی - نشریه الزویر

Abstract

Additively manufactured (AM) conformal cooling channels are currently the state of the art for high performing tooling with reduced cycle times. This paper introduces the concept of conformal cooling layers which challenges the status quo in providing higher heat transfer rates that also provide less variation in tooling temperatures. The cooling layers are filled with self-supporting repeatable unit cells that form a lattice throughout the cooling layers. The lattices increase fluid vorticity which improves convective heat transfer. Mechanical testing of the lattices shows that the design of the unit cell significantly varies the compression characteristics. A virtual case study of the injection moulding of a plastic enclosure is used to compare the performance of conformal cooling layers with that of conventional (drilled) cooling channels and conformal (AM) cooling channels. The results show the conformal layers reduce cooling time by 26.34% over conventional cooling channels.

6. Conclusion

Conventionally drilled channels in tooling are not capable of achieving optimal geometries for complex impression shapes in a balanced fashion. In order to overcome these short falls additive manufacturing is currently being adopted to manufacture conformal cooling channels. Whilst significantly increasing performance, the design of these cooling channels is often time intensive and are still restricted by design rules required to minimise uneven cooling. To overcome these limitations new conformal cooling layers with self-supporting lattice structures are introduced. The lattices are constructed from simple unit cells and designed with self-supporting angles for AM. The effectiveness of the cooling layers was verified via experimental testing and simulation. The lattice structures were found to increase heat transfer over circular channels due to increased interfacial surface areas and fluid vorticity. Simulations, which were verified by experimental data, showed significantly lower thermal gradients on the heated surface. The cooling layers are likely to find applications in high performance tooling were high heat transfer rates and/or thermal balancing is critical. Examples could include; injection moulding, blow moulding, extrusion and die casting. Compression testing revealed that the strength of the lattice structures will need to be carefully designed in order to prevent deflection in high pressure areas. The compression characteristics of the three lattice types were found to vary widely demonstrating how lattices could be used to tailor parts with a wide range of mechanical properties.