Our Design
“The Roller”
Shown below is a rendered image of our most recent design.
In lab tests the team found on that a large diameter roller a planar surface was the most effective method for crushing pills. The model shown in the image emulates the effect of rolling pills on a planar surface just as the team had done in lab. See the short video below for a demonstration of how the Blue Team’s pill crusher will operate.
As shown in the video, medication is placed in a sanitary and readily available polymer sleeve. This sleeve serves to isolate the medication from the crusher and also alleviates the risk of cross contamination between patient’s medications. The sleeve is then inserted to the crusher through an access slot. When inside the crusher, the sleeve rests on a small anvil plate. The operator then turns the handle which advances the plate and actuates the roller mechanism. Design constraints permit the roller to only move across the plate as if it were actually rolling across the surface without skidding. After several passes the medication should be adequately reduced and should be ready to be administered in the desired medium. See the Team Specifications page for information regarding our standards for evaluation and other test requirements.
Recorded below are several of “The Roller’s” key features:
Lab tests revealed that when pills initially crack before being completely crushed the 10” Diameter steel rollers we used had a tendency to “hop” or lift just slightly. On the second and third passes this “hop” was significantly reduced. To address this “hop” the anvil plate described above was designed as a beam with two supports. When pills are first rolled in the crusher this plate deflects to accommodate the “hop” we observed. At maximum deflection a force of 180 Lbs is being applied to the pills. The team found that 80lb was typical to initially crack the pills when they were most likely to induce a “hop.”
The Team used a variety of methods to evaluate what geometry was required to produce a specific load and deflection scenario. TK Solver is a simultaneous algebraic solver that has the function evaluating power of Excel and the ability to calculate missing variables. The image below is taken directly from the TK Solver interface and it shows a series of functions the Team was interested in. The functions model the Goodman method of failure for fatigue loading situations, i.e. cyclical loads that cause stress on the part to vary.
With the rules written a user inputs values they either know or would like to produce and TK Solver instantaneously calculates all other variables required to produce the scenario. This powerful method of solving equations allows the Engineer to design for any aspect of the component whether it be factor of safety or cross sectional geometry. The image below is an example solution that the Team considered.
Since cost is a significant consideration for this project several design features were preferred over others. As shown in the image above the anvil plate rests on a carriage which in turn slides over a rectangular rail. To ensure minimal friction at this interface PTFE bearing sheets are installed. These PTFE bearing sheets can be purchased for less than five dollars and show promise in being effective. Through innovative thinking and considering the customer’s needs, the Blue Team takes measures to use efficient components while potentially saving the customer hundreds of dollars per unit.