A new process of friction aided deep drawing has been developed. A metal blank holder was designed to be two layers: stationary layer with four planes of 5 degree taper angle and moving layer divided in to four tapered segments. Under appropriate blank holding force, these four segments can move radially to the die opening with a constant speed by using a specially designed compression tools. The main function of this divided blank holding device is adopting the frictional force between the blank and the blank holder to work in the useful drawing direction. Drawing deformation is efficiently performed by using an assistant metal punch. The drawing mechanism and the effects of drawing conditions are mainly investigated to characterize the merits and defects of the developed process. Deep cups of drawing ratio 2.87 have been produced with the present technique.

View full abstract

Rigid Media Tube Filter (RMF) is the most reliable treatment method to remove impurities from molten aluminum. The lifetime of RMF depends upon the amount of impurities normally filtered, but sometimes the molten aluminum insufficiently penetrates the RMF. The result of analyzing a half used cartridge insufficient positioning, namely, the centre and upper section of the cartridge show the lowest penetration ratio. We simulated a flow vector and velocity in a filter box by the Finite Element Method (FEM). The result of FEM shows that flow vector in the center of the filter box has the same result, slow velocity near the inside tubes, regardless of a inlet position. And also, the flow velocity at the tube's center is slower than that at both the inlet and outlet. The FEM result is similar to the actual result of the penetration ratio. It is assumed that low aluminum head pressure causes a lower penetration ratio in the upper section. In conclusion, we get similar result from FEM analysis and actual penetration ratio, however, penetration ratio is influenced by operational conditions and not merely flow in the filter box.

View full abstract

To investigate effect of additional Mn in thin brazing sheet (core alloy) on corrosion resistance, SWAAT and electrochemical measurements have been carried out with brazed Al–Mn–1.6 mass%Si alloys. Intergranular corrosion clearly occured in the alloys which Mn content is 1 mass% or less. In the case of these alloys precipitates of Si particle were observed at grain boundary, but they were not observed in grain after brazing. As a result, the potential difference between neighborhood of the grain boundaries and grain matrix became bigger. Therefore, selective dissolution occured at neighborhood of the grain boundaries which was lower solid solution of Si. On the other hand, intergranular corrosion were not observed in the alloys which Mn content is 1.6 mass% or more. In the case of these alloys fine precipitates of AlMnSi were observed in grain after brazing. As a result, the formation of Si-SDZ (solute depleted zone) by Si precipitation at grain boundary seen in the former alloys were inhibited. In conclusion, addition of Mn in thin brazing sheet had improving effect of corrosion resistance after brazing.

View full abstract