May 8, 2014
Senior Design is a year-long project in which Mechanical Engineering seniors participate at UPenn. The goal of the project is to build upon what students have learned in their core classes; teams generally consisted of 4 or 5 students per group. Our team's mission was to create a machine that more efficiently processed frozen fruit into soft-serve ice cream with no additives.
The project was an exercise in team dynamics. Without a cohesive and cooperative team, ideas have a hard time making it from the drawing board to the real world.
The Daily Pennsylvanian wrote an article about our project that sheds light on our accomplishments.
Conventional ice cream uses dairy and other added ingredients during the manufacturing process. Taking away these added elements makes it more difficult to achieve an optimal crystal size for the fruit. When dealing with just fruit, we had to break it down into a small enough crystal while maintaining an optimal serving temperature of -10°C. For this reason, we chose to integrate a freezer into the assembly of the system, which created difficult challenges that were unexpected.
The process of making frozen-fruit soft-serve ice cream, or "fruzi" as we referred to it, is currently being done through the use of a champion juicer. We modified the end of the juicer to allow for the tubing in the image (above). Fruit enters the diagonal end of the tube, the pressing mechanism would occur from the top end, and the hose attached towards the bottom would be for self-cleaning.
The gear box (above) was custom-machined (excluding the gears, which were ordered on-line), as were various other aluminum parts that helped support the structure of the machine. The gears were chosen such that a 90° rotation would result in a 8" vertical translation of a pushing piston. The sketch below shows the a few of our calculations in determining the proper sized gears and how they interact with the pushing piston.
In order to drive the system, we integrated a handle that was fixtured to the larger gear that ended driving the system. The sketch below show some early sketches of our handle and how it fixtures to the driving gear. Currently, the user of our champion juicer needed to exert a downward pushing force in order to push the fruit onto the grinder. Our handle lever is replacing this traditional method of pushing the fruit onto a juicer. Users of our device preferred the lever to the conventional pushing method since it's easier and it's a similar process to what is used on normal soft-serve ice cream machines.
To ensure concentricity, we turned the exterior diameter of the cylindrical stock (above). We then milled a slot to accomodate the gear that would soon be fixture to the rod (below).