Edge geometry of pipe blanks produced by JCOE flexure

Abstract

For the shaping of welded straight-seam large-diameter pipe in the TESA 1420 production line, methods are proposed for calculating the geometric parameters of the edge of the blank and the profile of the deforming tool. The edge geometry obtained on an edge-bending press is compared when using surface tools of involute and single-radius type. For tools of single-radius type, edge geometry consistent with the required shaping quality may be produced. For the edge-bending presses, a method of calculating the edge geometry in loading and unloading is outlined. The height of the bent edge, the residual radii of curvature, and the coordinates of the loading and unloading points at the external and internal edge contour of the pipe blank are determined. The coordinates of the edge formed by a tool with an involute profile are also calculated. The involute tool profile is universal on passing from one type of tool to another within a standardized group. The calculation permit conversion from an involute edge profile to a multiradial profile, followed by determination of the fixed coordinates of the points of the blank after springback. On the basis of those coordinates, the output edge geometry is estimated. Within the 1220–1420 mm standardized group, the longitudinal edge deformation for the 1220 × 10 mm type is calculated. Standardization is found to be much simpler with a single- radius tool profile. For edge-bending presses, a method of calculating the edge parameters of the pipe blank when using a tool with an involute contact profile is developed and tested in industrial conditions. Single- radius calibration of the profile of the edge-bending tool is proposed, such that fixed time coordinates are ensured. These are analogous to the coordinates with an involute punch profile. The blank’s weighted mean radius of curvature maximizes the agreement of the coordinates of the blank profile at fixed points in both approaches. (The maximum discrepancy is no more than 6–7%.)