A method for determining the relative position of a pair of platforms in an apparatus for supporting a roll former stand, wherein the apparatus has a pair of platforms on which a plurality of forming roll stands are disposed, and wherein each of the platforms is positioned symmetrically with respect to a workpiece flow direction, and a plurality of expandable links are connected between said platforms and a bed, wherein the positioning measuring method comprises:
- employing a certain coordinate to display positions of said pair of platforms;
- employing a certain coordinate to display a measured length of links being connected to each said platform;
- preparing an interchangeable map regarding the relative positional relationship between said two coordinates in advance;
- measuring the length of each expandable link;
- and
- obtaining desired coordinates on position and orientation of said platform through the interchangeable map by knowing the measured length of each link.