Analysis of deformation surrounding a hole produced by tube hydro-piercing

During tube hydro-piercing, the region adjacent to the pierced hole will be deformed and will be drawn away from the die block as the punch advances through the tube wall. The deformation in the region may range from a substantially flat form to a countersunk form. In the present study, the effects of tube material properties, punch diameter, tube wall thickness and internal pressure within the tube during piercing on the deformation behaviour have been investigated both experimentally and mathematically. The experimental results provide a clear relationship between the deformation radius and the rollover caused by the deformation. Using this relationship in the mathematical model allows for the prediction and for the control of the shape of the deformation region surrounding the hole, as a function of tube wall thickness, tube material strength, punch diameter and internal tube pressure.