Mechanism
The biggest challenge of this design is the rotating top. The top should be able to rotate, whilst still remaining watertight. This problem can then be divided in two parts, one being that the top should be able to rotate, and the second part being that the bottle should be watertight in the rotating connection.
Final design
The final design implements a snap fit in combination with a sealing ring, securing the parts in place, whilst still keeping it watertight. Even though this is a simple system, there are still some design considerations. A snap fit on two cylinders is not as simple as it is on some non-cylindrical objects.
Rotation
There are a number of options to make a system rotate in axial direction. There are complex solutions to this problem, which make it detachable, thus making it more cleanable. There are also more simple options, which make it easier to produce, thus less costly to make. However, these make it more difficult, if not impossible to remove the separate parts and to clean both parts. Once assembled, the final solution is not detachable anymore.
A nice feature is a little bump in the plastic at 0° and 180°, to indicate when the bottle is exactly straight and twisted. This improves the affordance of the bottle.
Solution: Snap fit
The best option is to make a snap fit. The top of the bottle can then easily be connected to the bottom part of the bottle, by simply snapping it on. In order to snap the parts together, the inner part must deform to get in place. This can be done in different ways, one way is to heat the material up above its glass transition temperature, making the material weaker, and thus easier to temporarily deform. Another way is to make some incisions around the cylinder. This results in several hooks which are more flexible, and thus possible to deform more easily. The favoured option is the latter, since this does not require more assembly steps to take place. Even if this system ends up still being too stiff after evaluation, an alternative would be to combine the both options, i.e. design the cylinders with incisions, and assemble it under elevated temperatures.
234 mm
60 mm
500 mL
The bottle consists of six parts and a rubber ring, of which three parts can be detached after assembly.
For more information on how the parts will be produced, go to manufacturing.
Height
Diameter
Volume