To safely and efficiency provide an alternative crushing method for the women of Uganda.
Problem Statement / Parameters
The women of Uganda need a rock crushing machine that will relieve the everyday stress from breaking rocks. These women spend long hours in the sun for little pay.
Rocks are broken from the parent rock and carried out of the quarry for the women to break into smaller sizes.
The type of rock is marble (metamorphic rock).
They currently use small handheld hammers to break rocks into smaller sizes.
Initial Design Considerations
Following the design process, Team Crusher formulated a House of Quality to transform the customers needs to engineering characteristics. We used Stuart Pugh’s total design matrix method which compared engineering characteristics of the clients needs to different available crushers on the market.
Considering power input, available resources, mechanical complexity and other engineering characteristics, we were able to eliminate and focus on specific designs. We found out most available crushers in the US are focused on output rather than hand operated or less output. Researching online for different rock crushing alternatives led us to our three paradigms: Jaw Crusher, Reverse Guillotine and Roller Crusher.
A jaw crusher was considered due to its size and versatility. Labour Intensive Technology and Engineering was working on devolving hand operated rock crushers and cement mixers for the workers in South Africa. Information on their project can be found here
The jaw crusher would be operated by single or double flywheels which would set the movable jaw in motion crushing the rocks. The size of the rock exiting the crusher can be specified by varying the gap between the two plates.
The only downside to the jaw crusher paradigm is that it wouldn’t be suitable for large rocks, approximately 8 inches diameter and greater.
The Reverse Guillotine was considered because of its simplistic design and effective use of energy. The idea originated from a Youtube video which can be found https://youtu.be/lwYWvsfzAPQ
The Reverse Guillotine would be ideal for larger rocks rather then smaller rocks. This paradigm would be used first in order to break the large rocks into smaller pieces for a different paradigm.
The Roller Crusher was considered due to its reduction ratio and consistent product size. The setbacks to the roller crusher include high maintenance from abrasive rocks against the roller/s and many moving parts.
After considering the paradigms the team constructed a prototype reverse guillotine crusher to determine if it was a suitable choice. As you can see from the following picture, the frame is constructed out of Bosch tubing and the platform, which the rock will be placed on, is attached to the bottle-jack underneath. The rock will be lifted by the bottle jack into a stationary blade mounted to the roof of the frame. This simple prototype was constructed to test the concept of the reverse guillotine. More tests are required to determine stresses in the frame so that proper material can be used. Also more data is required on the amount of force required to break varying sizes of rocks.
- Enlarge platform to minimum of 18” clearance
- Change frame from rectangular to A-frame for better strength and stability
- Swap Bosch Tubing for I Beams or Steel frame
- Weld the rock platform to the bottle jack
We recommend using two of the previous paradigms. First using the Reverse Guillotine paradigm to crush rocks, approximately 12 to 18 inches, into a more suitable size for the Jaw Crusher paradigm. The Jaw Crusher will then produce the final desired size for the Uganda woman.
The integration of the rock crusher into the system shall consist of attaching the reverse guillotine and the jaw crusher to the frame of the bike trailer. The attachment points will hinge to the trailer frame so that they may be folded up for ease of transportation. The reverse guillotine will be placed next to the jaw crusher so that crushed rock can easily move through the system.