METHOD FOR DETERMINING THE DIAMETER OF THE HOLE OF A HOLLOW MANDREL ON ITS FRONT END WITH SCREW PUNCHING IN A THREE-HIGH ROLLING MILL Russian patent published in 2023 - IPC B21B25/00 

FIELD: mechanical engineering.

SUBSTANCE: invention relates to a method for determining the diameter of the hole of a hollow mandrel on its front end for screw punching in a three-high rolling mill. Deformation is carried out by rolling in a three-high rolling mill of a workpiece whose diameter is equal to the diameter of the workpiece when punching in a three-high rolling mill using the aforementioned hollow mandrel. After the mentioned rolling of the workpiece along its radius, at least 7 points with an equal distance between them are selected. Hardness is measured at these points and these measurement results are displayed in the coordinate system. After drawing the points in the same coordinate system, a trend line is built using the applied points, reflecting the dependence of the hardness of the workpiece material on the distance from the center, the minimum hardness point of the workpiece is found on the resulting trend line and the distance from the center of the workpiece to the mentioned minimum point is determined. The distance found is multiplied by two and the resulting value is assumed to be equal to the diameter of the hole of the hollow mandrel at its front end.

EFFECT: as a result, the diameter of the hole of the hollow mandrel at the front end coincides with the diameter of the weakened annular zone.

1 cl, 3 dwg, 1 ex