Variable Contact Pressure and Variable Drawbead Height Influence on Deep Drawing of Al Alloys Sheets
The process of deep drawing is influenced by many factors. During the forming process, only two of those factors can be controlled. They are blank holding force and drawbead height. Realisation of such control requires relatively complex computerized apparatus. For this experimental research, electro-hydraulic sheet-metal strip sliding device has been constructed. Basic capacity of realized device is obtaining contact pressure and drawbead height as functions of time or stripe displacement. Additional features consist of the ability to measure drawing force, contact pressure, drawbead displacement etc. Presented in the paper are the results of influencing of increasing and decreasing drawbead height functions in combination with increasingdecreasing function of contact pressure. Stripe material is aluminium alloy AlMg4,5Mn0,7 sheet metal. Contact condition are additionally influenced by application of mineral oil or completely dry tool and stripe surfaces. Drawbead geometry, with rounding radii of 2 and 5 mm, is also varied. The accomplished results indicate that simultaneous effects of variable drawbead height, variable contact pressure, tool geometry and appropriate friction conditions can influence the plastic flow process in line with desired change of forming force.
Influence of Variable Blank Holding Force and Nonmonotonous Process of Deep Drawing on Formability of Coated Sheets
The results of the research of influence of the blank holding force and nonmonotonous process of deep drawing on the formability of low-carbon steel sheet with one-side galvanic coating of zinc are presented in this paper. Indetification and influence assessment was done by monitoring: forming force, the distribution of the principal strains in the sheet plane and their relationship to the forming limit diagram, changes of thinning strain and drawing depth as the most significant tehnological indicator. based on the analysis of test results, it was concluded that the blank holidng force has a significant influence in terms of intensified friction in the flange. Also, in terms of a sinfle-phase monotonous process, the applied type of variable blank holding force had a beneficial effect on the results of forming. A nonmonotonous two-phase process with uniaxial tenison in the first stage greatly affects the behaviour of materials.During the first phase, there is an increase of sheet anisotropy, which affects the formability decrease. The aplied variable holding force shows favourable effects, especially when friction was increased, but they were not dominant.
Remotely-Piloted Helicopter Citrus Yield Map Estimation
A remotely-piloted Gas Xcell mini-helicopter with GPS, wireless Ethernet, and a machinevision system was flown over orange trees to take overhead images. The individual tree images were processed to estimate the number of orange pixels in the images. The fruit yield of individualtrees at harvest a month later had an r-squared value of 0.373 with the number of orange pixels onthe irrigated tree images. While it was demonstrated that a remotely-piloted mini-helicopter could beused to acquire useful overhead images of citrus trees, substantial further research is needed toimprove the accuracy of estimates of individual tree yields or health.