are designated b 1 and b 2 in addition the rollers may include a flange forming portions designated 207 209 211 213 and 215 the rollers are generally mounted on shafts designated e with the number associated with each roller set the shafts e extend out to the associated sprockets and are driven by the chains as explained above and shown in fig5 in addition to the arc forming rollers tensioning roller sets 270 272 274 276 and 278 are interposed along the hook edge intermediate and alternating with the arc forming rollers along an opposite edge tension rollers 266 and 268 guide the material 120 and maintain proper tension so that the panels are formed correctly the roller sets 270 272 274 276 and 278 and the opposite roller 268 may be mounted about an angled axis of rotation and may have angled edges in order to maintain contact and facilitate proper tension as explained hereinafter as the blank panel material 120 is fed through the various forming roller sets the edges of the material 120 are bent and manipulated so that a horizontal roller may not be adequate to maintain proper pressure and alignment of the material as the material 120 is formed while passing through each successive roller set the angle and shape of the support needed changes as can be appreciated by those skilled in the art prior to engaging the arc forming rollers the material is first manipulated by passing through a punch station 220 having a punch roller 222 the rollers 222 include a plurality of punch members 224 projected radially.