| 摘要 |
PURPOSE:To remove residual stresses due to welding and prevent the form for a centrifugal molding from being deformed during repeated use thereof by a method wherein a tensile load is applied to the mold by using a preloader after welding the form. CONSTITUTION:The form for a centrifugal molding of concrete is manufactured to have a welded structure. After fixing mouthpieces 11 to flanges 6 at both ends of the form, a threaded rod 13 is screwed into the form. A frame body 8 is slidden by operating a handle 14 according to the length of the form, thereby regulating a distance l, and the frame bodies 7, 8 are connected in a fixed condition. Then, when the rod 13 is rotated by a driving force of a hydraulic jack 15 or the like, an axial tensile load is applied to the form. By applying said preload, the peak value of the residual stress due to welding is reduced to about one half of the original value. Accordingly, the form which is prevented from being deformed and is capable of operating smoothly at all times can be obtained easily. |
