For checkpoint 1, the following work was done:
Updated home page to reflect the concept, provide a basic explanation of rolling, and to explain the market need
Created lists of demands and specifications for the prototype and the counterpart real life machine
Selected materials and manufacturing processes for the real life machine, and how they can translate to building the prototype
Planned an initial testing method for the prototype, which can be found below.
In our small scale prototype, several criteria will be employed to determine the success of the machine. Our most important metric would be whether or not our rolling machine will perform its function to roll and flatten the plasticine we will be using to mimic steel at high temperature. The performance of our machine should be consistent in multiple trials of the same sized sample billets of plasticine, so we expect to test multiple samples during our demonstration and many more times during our fabrication of our scaled down machine. The mechanical motion of our machine should be smooth as well and never be rough or impede itself at any moment. A lack of smooth motion would cause uneven stresses in our final product.
Furthermore an analysis of the stresses our machine applies on the material could be conducted by using multiple colors of plasticine. The deformation would then carry out towards each color and trace out the lines of greatest stress and deformation.
An ideal test would consist of us loading one of our plasticine samples (all of which are uniformly created in a mold perhaps) into our machine. We would then activate our machine, run by DC motors, and it should roll the samples into thinner sheets. Hopefully, we should be able to get our final sheet within 3 passes of the machine, each pass with a uniform loading force measured with a load cell. We would remove the sample, look at the colored lines for a surface level analysis and load the next sample while resetting the machine. At the end, our samples should be the same dimensions and show relatively similar colored trace markings from the stresses of the machine. If these requirements are all met, then our machine successfully mimics a hot strip rolling machine, turning billets of material into longer, thinner sheets of material.
For checkpoint 2, the following work was done:
Create a model for the prototype machine
On the prototype model page, created charts with an overall summary of dimensions/forces and individual parts and processes
Performed calculations under the prototype model page for rolling force and torque required
Created an updated testing plan
Our most important metric in our new evaluation plan would still be whether or not our rolling machine will perform its function to roll and flatten the plasticine. To be more specific, we will be rolling 15 mm thick plasticine to 5 mm thick, in three passes, from 15 mm to 10 mm, 10 mm to 5mm, then 5 mm to 1mm. Smooth mechanic motion is necessary such that the machine will not impede itself. A lack of smooth motion would cause uneven stresses in our final product.
An ideal test would consist of us loading one of our plasticine samples (all of which are uniformly created in a mold perhaps) into our machine. We would then activate our machine, run by DC motors, and it should roll the samples into thinner sheets. Hopefully, we should be able to get our final sheet within 3 passes of the machine, each pass with a uniform loading force measured with a load cell. We would remove the sample, look at the colored lines for a surface level analysis and load the next sample while resetting the machine. At the end, our samples should be the same dimensions and show relatively similar colored trace markings from the stresses of the machine.
With roller radius of 25mm and slab width of 100mm, we approximate the flow stress to be 210 MPa resulting in a maximum force of 270 kN. With that, a torque of 1.50 kN*m will be produced using an approximation steel being rolled at 1200K. These forces are necessary to overcome the force of friction. In full scale, our machine will be conducting on steel and there are some considerations needed in order for scaling to be accurate. Although plasticine and hot worked metal have similar properties, it is important to note that the biggest difference is friction. In the real life machine, a larger torque must be applied to overcome the larger friction. In order to accommodate for the larger forces, overall dimensions in the structural frame and roller must be increased. It is important to note that we cannot linearly scale the dimensions of our prototype machine, but we can assume that the forces to linearly scale for the plasticine to behave like steel at high temperatures.