A prototype case with thin internal fins was created in the development of a Stirling engine with performance that exceeds that of conventional compact Stirling engines. Radial grooves are cut into the pistons located inside the case in order to avoid these fins, and high accuracy is called for to help prevent contact between the pistons and fins during operation.Since conventional manufacturing processes are unable to satisfy these specifications, precise manufacturing was realized for the first time through additive manufacturing, that is to say, the use of a 3D printer for metal materials. However, there are also many locations where the needed specifications cannot be satisfied simply by existing additive manufacturing technology, so various manufacturing process know-how was needed.Selection of the blade used to laminate the powder, use of reinforcing rings that are removed after molding, machining of small holes to remove powder remaining inside the structure before heat treatment, and other techniques were obtained as know-how. In addition, it was found that given sufficiently short length, molding can be performed even with a plate thickness of 0.5 mm.
Article of Honda R&D Technical Review Vol.28 No.1 (174 - 182)