INTERNAL MOLD FOR CYLINDRICAL CONCRETE PRODUCT

PROBLEM TO BE SOLVED: To easily demold an internal mold by increasing a rate by which the diameter of the internal mold is contracted, and increase the dimensional precision and the durability as well. SOLUTION: The peripheral wall is divided in the vertical direction into four dividing sections and four intermediate sections located between respective dividing sections. A moving means which moves respective dividing sections in the central direction or in the outer peripheral direction, and an interlinking means which interlinks respective intermediate sections in the central direction when respective dividing sections are moved in the central direction by the moving means are provided. By providing the dividing sections at four locations, the rate by which the diameter of the internal mold is contracted becomes larger. Also, there is no hinge section on the peripheral wall, and therefore, the dimensional precision of this concrete product and the durability of the internal mold are increased.