SHIPPING CONTAINER
I was assigned to build a door for a 40ft shipping container. However this door is different from the regular ones that open to the side, it instead will be opened via an upward motion whereby the door will end up on the top of the container.
To make this mechanism work, I had to implement the knowledge behind a 4-bar mechanism and use pin joints at the various points. However, before creating the CAD parts and models, I needed to determine where the arms would be placed. For this purpose, I used a tool called Math Illustrations. With this tool, I am able to plot, on a smaller scale, the designated positions I want the arm of the container to be at for 3 different positions. With this, I can play around with the line segments, until a point whereby if I were to generate a circle around ‘OA’ and ‘OB’, they would intersect all 3 points I want. For instance, A – A’ – A’’ and B – B’ – B’’. As seen in Figure 1, I managed to get all the points to intersect via a circle for both OA and OB. From this, I can get the coordinate points necessary, and scale the measurements up to fit an actual 40ft shipping container.
Figure 1 - Math Illustrations
I created all the necessary parts and assembled them in Creo. The movement of the arms is shown in the video and screenshots of still images of the arms at 3 different locations are shown below.
Figure 2a - Start of Mechanism
Figure 2b - Middle of Mechanism
Figure 2c - End of Mechanism
Video of Mechanism
Evaluation
After several failures and unsuccessful building, I finally managed to get the cover to lay flat on top of the container.
I observed several improvements I could make to this design. Firstly, I should have used retainer rings as they ensure the arms do not come loose but allow for the movement of the arms. Secondly, the arms should be wider to withstand the force and mass of the material, to prevent the arms from breaking.
This assignment taught me the importance of designing and dimensioning. Even though a calculation and/or observation may seem correct on one platform, may not turn out the way one expects it to be, and will have to make various modifications based off the foundation they created.