[Series] How the US-2 is made (2)
Close coverage by a professional writer
Molding of parts
—A process that combines craftsmanship and chemistry
The parts of the US-2 cut out from aluminum alloy sheets are still flat and look like development drawings. These parts are bent, drilled, and processed to create the specified shapes.
A press brake that can bend plates to any curve or angle, a hydraulic press that sandwiches a sheet between dies and applies strong pressure to form a shape in an instant, and other machine tools are used in this process. Furthermore, parts with complex shapes that cannot be machined with these machines are hammered and bent by the hands of craftsmen.
Soft and thin aluminum alloy sheets are better suited for this bending process. However, they are not strong enough for use in the US-2.
Therefore, we apply a process called “heat treatment”. Certain aluminum alloy materials have the property to harden when they are left at room temperature for a certain period of time after being heated and this property is used for parts that require strength.
Specifically, to harden the parts, an oven is used to expose the parts to high temperatures for a specified period of time. Then, they are brought back to room temperature. This expertise is a precious asset that has been passed down for about 80 years, going back to the time when ShinMaywa was manufacturing amphibians as Kawanishi Aircraft Company.
(1) Use of a press brake enables bending a sheet into the desired shape in an instant. It can also produce gently curved shapes such as the surface of an airframe. However, this requires experienced skill.
(2) This is a hydraulic press. The sheet material is set in the die and pressed into the desired shape by the press shown in the back. This is suitable for the mass production of parts with the same shape.
(3) The US-2 has only one part that cannot be shaped by the press machine. So a skilled craftsmen bends it by carefully using a hammer.
(4) This is a part of the US-2 machined by a press brake. This shape can be obtained only by following a specific procedure.
(5) An oven to harden aluminum alloy materials through heat treatment. The burn marks on the door tell of how its high temperatures. Only the certified operators in the company are allowed to operate.
(6) After heat treatment, the door opens and a rack containing the materials comes out, which is immediately immersed in the chemical solution at once and cooled rapidly. This process naturally strengthens the material.
(7) This is a part of the US-2 after the bending process. The next process is surface treatment.
Writer Hidenori Itakura
- *This series is produced and published with the permission of the Ministry of Defense. Please do not reproduce the content and images of this series.
