Project 4: The blister
Introduction
This is the fourth project for BEIL0014 I have been working on, which is hammering out a blister on a sheet of aluminium with aid of a hollow double sided wood mold . My objective is to create a blister that has a clear edge with maximizing its depth.
Theory
As I have been given a relatively big mold for this project, which means there is more metal available to be stretched out, my aim is to let the metal reaching its ultimate strength. The following shows a graph of metal behavior of stress vs strain.
Before the sheet metal fracture, the metal will undergo strain hardening which become harder and harder as it stretches. My strategy was to apply this theory and hammer the metal evenly at constant strength so that the unstretched part will keep stretching and the fully stretched part will stop stretching. This will keep me from breaking the sheet metal.
Procedure
To begin with, I place the sheet metal between two molds and drilled four holes in the corner. Then I add 4 screw each at the holes that I drilled before. This is used to stabilize the sheet metal as I hammer it.
After that, I put two plank of wood on each side of the wood mold to increase the ground clearance, next I clamp the whole thing to stabilize the set up as hammering will movement to the product.
Next, I took a stick of wood and sharpen it at the grinder, then with aid of the stick I was able to hammer the edge to the mold to give a distinctive look of the blister.
The whole process I used plastic head hammer to give a smooth surface. Then hammer it with constant strength until is nearly reaches its ultimate strength
The finish product are shown as follow:
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