Method and device for producing concrete pile

A manufacturing method of a concrete pile that uses a formwork in which a drainage hole connected to outside is provided on a molding surface and in which a pile molding space can be reduced and enlarged, the method comprising:

• pouring concrete in the pile molding space, reducing the pile molding space to compress and mold the concrete, draining water drained from the concrete by compression and molding outside of the formwork from the drainage hole, and holding the concrete a predetermined amount of time to harden the concrete,
• wherein,
• the formwork includes an outer formwork that molds an outer wall surface of the concrete pile, an inner formwork that molds an inner wall surface of a hollow space of the concrete pile, and a pair of end formwork that mold upper and lower end surfaces of the concrete pile,
• the outer formwork includes a plurality of components that are linked with a hinge, the drainage hole is a slit shape, the drainage hole is a gap between the adjacent components when the mold is tightened, and the gap is configured to be capable of being opened larger during cleaning than when the mold is tightened,
• an inner side surface of the drainage hole is opened toward an inner surface side of the outer formwork when the components linked with the hinge are opened,
• the inner formwork includes a pair of cores each including a tapered surface which shrinks in diameter toward a tip along an axis direction of the pile molding space and the tips are positioned to face each other,
• the end formwork is configured to be capable of supporting a rear end of the pair of cores in a slidable manner,
• a cylinder device slides at least one core along the axis direction and brings close and separates the tips of the pair of cores, and wherein the cylinder device includes a cylinder tube and a piston rod and is configured to be capable of reducing and enlarging the pile molding space,
• the pair of end formwork include a hole through which both ends of a tension material extending in the axis direction in the pile molding space are able to penetrate and are able to extend outside of the end formwork,
• a flange and a first fastener latches both ends of the tension material extending from the hole to the pair of cores, and a second fastener that latches both ends of the tension material extending from the hole to the pair of end formwork,
• in addition to using the flange and the first fastener, the cylinder device is used to extend the pair of cores in the axis direction, the pile molding space is enlarged, and tensile stress can be created in the tension material, and
• the second fastener is configured to be capable of being used to constrain the tension member in a state that tensile stress is created by the outer formwork and the end formwork.