Manufacturing method and manufacturing equipment for concrete piles
Technical field
[0001]
　The present invention relates to a method for manufacturing a concrete pile and a manufacturing apparatus.
Background technology
[0002]
　Patent Document 1 describes a technique for compression-molding concrete by reducing the molding space as a technique for manufacturing concrete piles at low cost and with low noise in place of a large centrifugal molding machine.
　In Patent Document 1, a member made of a water-permeable material such as hard urethane is arranged in a formwork to provide a storage space for drainage from concrete by compression molding.
prior art literature
Licensed Literature
[0003]
Patent Document 1: Japanese Patent Application Laid-Open No. 2015-142966
Outline of the invention
Problems to be solved by the invention
[0004]
　According to the above-mentioned prior art, a part of the molded surface may be made of a water-permeable material such as hard urethane, but it is deformed by pressure during compression molding, and it is difficult to mold a concrete pile with high dimensional accuracy. Further, when the pressure during compression molding is suppressed to be low in order to suppress deformation, the strength of the concrete pile cannot be increased.
　In addition, drainage from concrete stays at the water retention capacity of water-permeable materials such as hard urethane placed in the formwork, and there is a risk of insufficient drainage. Therefore, concrete piles are manufactured with the desired moisture content and desired strength. Difficult to do.
[0005]
　The present invention has been made in view of the above problems in the prior art, and an object of the present invention is to manufacture concrete piles at low cost, low noise, high drainage efficiency, high accuracy and high strength.
Means to solve problems
[0006]
　In the method for manufacturing a concrete pile according to one aspect of the present invention, concrete is put into the pile forming space by using a formwork in which a drain hole communicating with the outside is provided on the forming surface and the pile forming space can be reduced and expanded. Then, the pile forming space is reduced to compression-mold the concrete, and the water discharged from the concrete by the compression molding is drained from the drain hole to the outside of the formwork and held for a predetermined time to hold the concrete. Let it cure.
[0007]
　The concrete pile manufacturing apparatus of one aspect of the present invention is a concrete pile manufacturing apparatus provided with a formwork for compression-molding the concrete pile, and a drain hole communicating with the outside is provided on the molding surface of the formwork. The formwork makes it possible to reduce and expand the pile forming space for compression forming concrete piles.
The invention's effect
[0008]
　According to the method for manufacturing a concrete pile according to one aspect of the present invention, the concrete pile can be manufactured with high accuracy and high strength at low cost and low noise.
[0009]
　According to the concrete pile manufacturing apparatus of one aspect of the present invention, the concrete pile can be manufactured with high accuracy and high strength at low cost and low noise without using a large-scale device other than the formwork. can.
A brief description of the drawing
[0010]
FIG. 1A is an axial sectional view of a concrete pile manufacturing apparatus according to an embodiment of the present invention.
FIG. 1B is a cross-sectional view taken along the line BB of FIG. 1A.
FIG. 2 is an axial sectional view of a concrete pile manufacturing apparatus according to an embodiment of the present invention, showing a state in which a pair of cores are drawn to the center of the apparatus.
FIG. 3 is a partial cross-sectional view in a direction perpendicular to the axis of the concrete pile manufacturing apparatus according to the embodiment of the present invention, and is a diagram showing details of an outer formwork drainage portion. Shows a cross section without a magnet.
FIG. 4 is a partial cross-sectional view perpendicular to the axis of the concrete pile manufacturing apparatus according to the embodiment of the present invention, and is a diagram showing details of an outer formwork drainage portion. Shows a cross section with a magnet.
FIG. 5 is a perspective view showing details of an outer formwork drainage portion which is a part of a concrete pile manufacturing apparatus according to an embodiment of the present invention.
FIG. 6 is a schematic cross-sectional view perpendicular to the axis of the concrete pile manufacturing apparatus according to another embodiment of the present invention.
FIG. 7 is a schematic cross-sectional view perpendicular to the axis of the concrete pile manufacturing apparatus according to another embodiment of the present invention.
FIG. 8 is a schematic cross-sectional view perpendicular to the axis of the concrete pile manufacturing apparatus according to another embodiment of the present invention.
FIG. 9 is a schematic cross-sectional view perpendicular to the axis of the concrete pile manufacturing apparatus according to another embodiment of the present invention.
FIG. 10 is a schematic cross-sectional view perpendicular to the axis of the concrete pile manufacturing apparatus according to another embodiment of the present invention.
FIG. 11 is an axial cross-sectional view of a concrete pile manufacturing apparatus according to an embodiment of the present invention, showing a state of manufacturing two concrete piles having an arbitrary length shorter than the axial length of a pile forming space. There is.
FIG. 12 is an axial cross-sectional view of a concrete pile manufacturing apparatus according to an embodiment of the present invention, showing a state of manufacturing a single concrete pile having an arbitrary length shorter than the axial length of a pile forming space. There is.
FIG. 13 is a perspective view showing details of an outer formwork drainage portion which is a part of a concrete pile manufacturing apparatus according to another embodiment of the present invention.
FIG. 14 is a plan view showing an example of the arrangement of slits.
FIG. 15 is a plan view showing another example of the arrangement of slits.
FIG. 16 is a plan view showing another example of the arrangement of slits.
FIG. 17 is a plan view showing another example of the arrangement of slits.
FIG. 18 is a top view of a manufacturing facility for explaining a method for manufacturing a concrete pile according to another embodiment of the present invention.
FIG. 19 is a top view of a tensioning material and a manufacturing facility for explaining a method for manufacturing a concrete pile according to another embodiment of the present invention.
FIG. 20 is a top view of a manufacturing landscape for explaining a method for manufacturing a concrete pile according to another embodiment of the present invention.
FIG. 21 is a top view of the manufacturing landscape following FIG. 20.
FIG. 22 is a top view of the manufacturing landscape following FIG. 21.
FIG. 23 is a top view of the manufacturing landscape following FIG. 22.
FIG. 24 is a top view of the manufacturing landscape following FIG. 23.
FIG. 25 is a top view of the manufacturing landscape following FIG. 24.
FIG. 26 is a cross-sectional view of an outer formwork body which is a part of a concrete pile manufacturing apparatus according to still another embodiment of the present invention, and shows an open state.
FIG. 27 is a cross-sectional view of an outer formwork body which is a part of a concrete pile manufacturing apparatus according to still another embodiment of the present invention, and shows a closed state.
Embodiment for carrying out the invention
[0011]
　Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The following is an embodiment of the present invention and does not limit the present invention.
[0012]
[Outline 1 of the embodiment]
(Equipment configuration)
　As shown in FIGS. 1A and 1B, the concrete pile manufacturing apparatus 100 of the present embodiment includes an outer formwork body 10 assembled in a substantially square cylinder shape and an outer formwork. It includes an inner formwork 20 arranged inside the main body 10 and a stake formwork 30 that closes the openings at both ends of the outer formwork main body 10.
[0013]
　The outer formwork main body 10 is assembled so that a steel rod 1 extending in a predetermined direction and a pair of joint metal fittings 2 fixed to both ends of the steel rod 1 can be accommodated therein.
　The steel rod 1 is, for example, a prestressed concrete steel rod (PC steel rod), and is a core material that serves as a reinforcing reinforcing bar for a concrete pile such as a concrete pile. That is, the steel rod 1 is a reinforcing material and a tensioning material for introducing prestressed concrete. As the tension material, other materials such as PC steel wire, PC steel stranded wire, and carbon fiber tension material may be applied.
　The joint hardware 2 is a steel plate-shaped member having an opening formed in the center thereof, and is a member that becomes a joint end plate of a concrete pile such as a concrete pile.
　Both ends of the steel rod 1 are fixed to the joint metal fitting 2 by a fixing tool such as a bolt, and the steel rod 1 and the pair of joint metal fittings 2 are integrated. In this embodiment, twelve steel rods 1 are bridged between a pair of joint hardware 2.
[0014]
　The inner formwork 20 has a tapered surface whose diameter is reduced toward the tips 21a and 22a along the direction in which the steel rod 1 housed in the outer formwork body 10 extends (axial direction of the steel rod 1). It is composed of a pair of cores 21 and 22 whose tips are arranged so as to face each other.
　An opening 23 is provided on the tip 21a side of one core 21, and a protrusion 24 inserted into the opening 23 is provided on the tip 22a side of the other core 22.
　The opening 23 provided at the tip 21a of the core 21 is a cylindrical member, and has a size in which the protruding portion 24 is in sliding contact with the inner peripheral surface thereof.
　The protruding portion 24 provided at the tip 22a of the core 22 is a cylindrical member extending along the axial direction of the steel rod 1, and its outer peripheral surface is in sliding contact with the opening 23 and moves in the pipe axial direction. It has a possible shape. Further, the sliding surfaces of the cores 21 and 22 are provided with a considerable length to prevent the inner form 20 from loosening.
　Therefore, in a state where the inner formwork 20 is provided in the outer formwork body 10, a pile forming space S into which concrete is put is formed between the tapered surface of the inner formwork 20 and the outer formwork body 10. The formwork.
[0015]
　Further, the pair of cores 21 and 22 of the inner form 20 has a hollow portion inside, and the cores 21 and 22 are moved in the hollow portion along the axial direction of the steel rod 1. A cylinder device 40 is provided.
　The cylinder device 40 is, for example, a double-acting hydraulic cylinder, and includes a cylinder tube 41 and a piston rod 42. The cylinder tube 41 is connected to one core 21 and the piston rod 42 is connected to the other core 22. In particular, the cylinder tube 41 is connected to the core 21 via a connecting pin 43 that can be opened and closed by remote control to switch the attachment / detachment state.
　By operating the cylinder device 40 to move the piston rod 42 back and forth with respect to the cylinder tube 41, the tip 21a of one core 21 and the tip 22a of the other core 22 can be brought close to each other or separated from each other. .. Then, by moving the pair of cores 21 and 22 closer to or further from each other by the cylinder device 40, the opening 23 provided at the tip 21a of one core 21 and the tip 22a of the other core 22 are formed. The pair of cores 21 and 22 can be slid so as to move in sliding contact with the provided protrusion 24.
[0016]
　The formwork 30 is arranged at both ends of the outer formwork body 10 in the longitudinal direction.
　The formwork 30 is provided with recesses 30a that slidably support the rear end portions 21b and 22b of the cores 21 and 22 constituting the inner formwork 20.
　Further, an elastic cushioning material 50 is provided on the inner surface of the formwork 30, and a pair of joint metal fittings 2 fixed to both ends of the steel rod 1 housed in the outer formwork body 10 are cushioned. It is in contact with the formwork 30 via the material 50. The cushioning material 50 is, for example, a plate-shaped member made of styrofoam or a hard sponge, and has an opening formed on the center side like the joint hardware 2.
[0017]
　The outer form drainage portions 60 are arranged at the four corners of the outer form main body 10. Together with the outer formwork body 10 and the outer formwork drainage section 60, it corresponds to an outer formwork that forms the outer wall surface of a concrete pile.
　As shown in FIG. 3, the outer form drainage portion 60 includes a holding portion 61 and a perforated molded plate 62. The perforated molded plate 62 is held by the holding portion 61. The perforated forming plate 62 forms a forming surface for forming the outer wall surface of the concrete pile. Further, depending on the structure, the holding portion 61 also forms a forming surface for forming the outer wall surface of the concrete pile, but the holding portion 61 does not form the forming surface, that is, the holding portion 61 is not exposed to the pile forming space S. It may be configured as.
　The perforated molded plate 62 is provided with a drain hole 62a. The drainage hole 62a communicates with the outside.
[0018]
　Further, the water permeable filter 63 is installed so as to cover the drainage hole 62a on the molding surface provided with the drainage hole 62a of the perforated molded plate 62. By using the water permeable filter 63, it is possible to prevent clogging of the drain hole 62a and adhesion of concrete to the perforated molded plate 62, and it is possible to realize low maintenance in repeated use of the perforated molded plate 62 and to be productive. Is improved. Further, by using the water permeable filter 63, it is possible to prevent or reduce the transfer of the trace of the drainage hole 62a to the concrete surface, and the concrete pile can be formed finely. The water permeable filter 63 can quickly recover drainage by replacing it with an unused water permeable filter 63 every time as a disposable specification, and can extend the service life of the perforated molded plate 62, thus achieving low maintenance and low cost. While achieving this, productivity can be improved.
　As described above, the formwork of the present manufacturing apparatus 100 is dispersed in all directions around the axis of the pile forming space S, and drainage holes 62a are provided. The positions of the drain holes 62a are dispersed to improve the drainage property. The term "axis" for the pile forming space S refers to an axis corresponding to the axis of the concrete pile formed by the pile forming space S.
　In the present embodiment, an octagonal cross section in which a cross section perpendicular to the axial direction of the pile forming space S is cut out from a rectangular cross section formed by the outer formwork body 10 by a short side formed by the outer formwork drainage portion 60. And said. The octagon is an octagon in which long sides and short sides are alternately connected, and the drain holes 62a are dispersed in all directions by arranging the drain holes 62a on the short sides.
[0019]
　The holding portion 61 may be formed as an integral part of the outer form main body 10 or fixed to the outer form main body 10 by welding or the like.
　The drainage hole 62a is not limited to the one shown in the figure, and may have a shape that extends outward from the open end on the molding surface. The drainage property can be further improved.
[0020]
　The perforated molded plate 62 constitutes the drainage hole 62a and the molding surface of the portion where the drainage hole 62a is provided, and is removable from the holding portion 61. For example, the perforated molded plate 62 is made of a material capable of magnetically adsorbing such as a steel plate, and the magnet 64 is fixed at a predetermined position of the holding portion 61 as shown in FIGS. 4 and 5, so that the perforated molded plate 62 is formed. It can be attracted and held by the magnetic force of the magnet 64 and can be removed. By removing the perforated molded plate 62, cleaning and maintenance such as clearing the clogging of the drain hole 62a can be easily performed. Further, after the pile is manufactured, by replacing the perforated molded plate 62 used at the time of manufacturing with a new or cleaned perforated molded plate 62, it is possible to quickly move to the next pile manufacturing and it has been used. Since the maintenance time of the perforated molded plate 62 can be taken, the manufacturing efficiency is improved.
　The magnets 64 are provided at several to a dozen places (depending on the length) along the longitudinal direction of the holding portion 61 corresponding to the axial direction of the concrete pile, and the drain holes 62a are provided between the magnets 64. Leave it as a drainage route to the outside.
[0021]
(Manufacturing Method)
　Next, a method for manufacturing a concrete pile using the concrete pile manufacturing apparatus 100 will be described.
[0022]
　First, a plurality of (for example, 12) steel rods 1 are attached so as to be bridged between a pair of joint hardware 2.
　A long square tubular outer formwork body 10 is assembled in the extending direction of the steel rod 1 so as to accommodate the steel rod 1 fixed between the pair of joint hardware 2 inside.
　Further, a perforated molded plate 62 to which the water permeable filter 63 is attached is attached to the holding portion 61 at the corner of the outer form main body 10 (see FIGS. 3 and 4).
[0023]
　Next, one core 21 is inserted through the opening of one joint hardware 2, and the other core 22 is inserted through the opening of the other joint hardware 2. A piston rod 42 is connected to the other core 22, and a cylinder device 40 is attached to the core 22 side.
　Then, at substantially the center between the pair of joint hardware 2, the protrusion 24 provided at the tip 22a of the other core 22 is inserted into the opening 23 provided at the tip 21a of one core 21. Then, a pair of cores 21 and 22 are assembled in a state where the protrusion 24 is inserted through the opening 23.
　Further, when the protruding portion 24 of the core 22 is inserted into the opening 23 of the core 21, the cylinder tube 41 of the cylinder device 40 attached to the other core 22 is inserted into the one core 21. .. When the cylinder tube 41 reaches a predetermined position in the core 21, the connecting pin 43 is operated by remote control to connect the cylinder tube 41 to the core 21.
　By connecting the pair of cores 21 and 22 via the cylinder device 40 in this way, when the cylinder device 40 is operated, the tip 21a of one core 21 and the tip 22a of the other core 22 are connected. An inner formwork 20 that can be brought close to or separated from each other is assembled.
[0024]
　Next, the cushioning material 50 is sandwiched between the joint hardware 2 and the formwork 30, and the formwork 30 is fixed to both ends of the outer formwork body 10. At this time, the rear end portions 21b, 22b of the cores 21 and 22 constituting the inner formwork 20 are fitted into the recesses 30a of the formwork 30, and the formwork 30 is assembled to the outer formwork body 10.
　In this way, the concrete pile manufacturing apparatus 100 is assembled in the state shown in FIGS. 1A and 1B.
[0025]
　Next, concrete is poured from the input port (not shown) provided in the outer formwork main body 10, and the outer formwork main body 10, the outer formwork drainage portion 60, and the inner formwork are between the pair of joint hardware 2. Concrete is put into the pile forming space S between 20. At this time, the cylinder device 40 is operated so that the pair of cores 21 and 22 are repeatedly moved forward and backward so as to promote the fluidity of the concrete and fill the pile forming space S with the concrete. Is preferable.
　Then, after filling the pile forming space S with a predetermined amount of concrete, the input port (not shown) is closed.
[0026]
　Next, as shown in FIG. 2, the cylinder device 40 is operated so as to pull the piston rod 42 into the cylinder tube 41, and the tip 21a of one core 21 and the tip 22a of the other core 22 are brought close to each other.
　The pair of cores 21 and 22 having a tapered shape that tapers toward the tips 21a and 22a are attracted to the center side of the manufacturing apparatus 100 so that the tips 21a and 22a are close to each other, whereby the concrete is formed. The filled pile forming space S is compressed, the internal pressure in the pile forming space S rises, and the concrete is in a pressurized state. The water discharged from the concrete is drained to the outside of the formwork from the drain hole 62a.
　Then, the pair of cores 21 and 22 are held for a predetermined time in a state of being pulled toward the center side of the apparatus so that the internal pressure of the concrete in the manufacturing apparatus 100 becomes a set value, and the concrete is hardened.
　In FIG. 2, the concrete filled in the pile forming space S is not shown.
[0027]
　Here, a step of holding a state in which the tips 21a and 22a of the pair of cores 21 and 22 are close to each other for a predetermined time will be described.
　When the pair of cores 21 and 22 are pulled toward the center side of the manufacturing apparatus 100, the pile forming space S between the pair of joint hardware 2 is compressed, and the concrete filled in the pile forming space S is uniformly pressurized. Therefore, a pressing force acts on the joint metal fitting 2 facing the pile forming space S, and the pair of joint metal fittings 2 are pressed in a direction away from each other and pressed toward the mold frame 30.
　At this time, since the cushioning material 50 is interposed between the joint metal fitting 2 and the formwork 30, the steel rod 1 is stretched when the pair of joint metal fittings 2 are pressed against the formwork 30 respectively. Is absorbed by the cushioning material 50 and the pretension is introduced into the steel rod 1.
　By pressure-holding the concrete filled in the pile forming space S in this way, pretension can be introduced into the steel rod 1, and by further pressure-holding and hardening the concrete for a predetermined time, prestress is introduced. Prestressed concrete is introduced into the concrete after the demolding of the inner formwork 20 by the steel rod 1.
　Since the amount of movement of the pair of cores 21 and 22 to the center side of the manufacturing apparatus 100 depends on the excess water and air in the concrete, the correlation between the concrete composition and the change in the volume and the internal pressure of the concrete is determined in advance. By setting aside, the internal pressure of the concrete can be adjusted to a desired set value in a state where the tips of the cores 21 and 22 are in contact with each other.
　Further, if the concrete is pressure-held and hardened while the tips of the cores 21 and 22 are in contact with each other, the hardened concrete is in contact with the tapered surface of the cores 21 and 22, so that the inner formwork 20 is used. Demolding becomes easy.
[0028]
　Next, the state in which the pair of cores 21 and 22 are attracted to the center side of the manufacturing apparatus 100 is maintained, the concrete in the manufacturing apparatus 100 is pressed and held for a predetermined time to harden the concrete, and then the piston is formed from the cylinder tube 41. The cylinder device 40 is operated so as to push out the rod 42, and the tips 21a and 22a of the pair of cores 21 and 22 are moved so as to be separated from each other to remove the inner form 20.
　Further, after the formwork 30 is removed from the mold, the connecting pin 43 is operated by remote control to remove the cylinder tube 41 from the core 21 and remove one core 21 and the other core 22, respectively. Further, the outer formwork main body 10 is removed from the mold to obtain a concrete pile.
　Then, the demolded concrete pile is completed after being wet-cured at a high temperature, for example, individually covered with a sheet and steam-cured.
　As described above, the prestressed concrete pile (PC pile) in which the prestressed concrete is introduced into the concrete can be manufactured by the steel rod 1 into which the prestressed concrete is introduced.
　In addition to the pretension method described above, a post tension type PC pile can also be manufactured by the present manufacturing apparatus 100. The main points when manufacturing a post-tension type PC pile are as follows. Instead of the steel rod 1, a sheath and a PC steel material passed through the sheath are installed in the outer formwork main body 10 so as to connect the pair of joint hardware 2. At that time, both ends of the PC steel material are installed so as to extend through the holes provided in the pair of joint hardware 2. It is not necessary to install the cushioning material 50. Others are carried out in the same manner, and after the concrete of the demolded concrete pile is hardened, tension is applied by pulling both ends of the PC steel material, and prestress from the pair of joint hardware 2 is introduced into the concrete. After the tension of the PC steel material, grout is injected into the sheath to integrate the concrete and the PC steel material.
[0029]
　As described above, the concrete pile manufacturing apparatus 100 of the present embodiment has a simple structure and the manufacturing apparatus 100 can be easily installed and removed. Therefore, the manufacturing apparatus 100 is installed at the construction site. Therefore, it becomes possible to manufacture concrete piles using ready-mixed concrete and on-site kneaded concrete at each construction site.
　If concrete piles can be manufactured at the construction site, large factory equipment will not be required, and the cost of transporting heavy concrete piles from the factory to the construction site can be reduced. It is possible to reduce the construction cost.
　Further, in the manufacturing method using the concrete pile manufacturing apparatus 100, there is no need to perform centrifugal molding or vibration compaction as in the prior art, so that it is not necessary to excessively reinforce the formwork and the formwork. Since it is less likely to be damaged and maintenance is easy, the maintenance cost of the manufacturing apparatus 100 can be reduced, and the product cost and the construction cost can be reduced. Furthermore, since it is not accompanied by noise or vibration, there is no impact on the surrounding environment of the site.
　That is, according to the method for manufacturing a concrete pile using the concrete pile manufacturing apparatus 100 of the present embodiment, a concrete pile such as a concrete pile can be manufactured at a low cost, and the construction can be performed at a low cost.
[0030]
　Further, by adopting the inner formwork 20 composed of a pair of cores 21 and 22 that are closely separated by the cylinder device 40 for the manufacturing device 100, concrete filled in the pile forming space S in the manufacturing device 100 is suitable. Since the excess water and air contained in the concrete can be satisfactorily discharged, it is possible to form a solid concrete without compaction such as centrifugal force and vibration. , High strength and high quality concrete pile can be manufactured.
　Further, by providing the outer formwork drainage section 60 at the corner of the outer formwork main body 10 in the manufacturing apparatus 100, the drainage of excess concrete water is facilitated and the W / C (water-cement ratio) is reduced. It is possible to improve the strength of concrete piles. At this time, since the outer form drainage portion 60 has a molded surface formed by a perforated molded plate 62 in which drainage holes 62a are provided in a structural material such as a steel plate, there is no possibility of deformation due to pressure during compression molding. , Concrete piles can be molded with high accuracy. Further, since the drainage hole 62a communicates with the outside, there is no possibility of insufficient drainage, and the concrete pile can be manufactured with a desired W / C (water-cement ratio) and a desired strength.
[0031]
　Further, when the concrete is hardened, the concrete is pressed by the cores 21 and 22 of the inner formwork 20, so that a pressing force acts on the pair of joint hardware 2 in a direction away from each other to form a joint. Since the pretension is introduced in the axial direction of the steel rod 1 fixed to the hardware 2, the prestressed concrete is introduced into the concrete after the inner formwork 20 is demolded.
　Therefore, when manufacturing a concrete pile, it is not necessary to separately prepare a special tool or device for introducing the pretension to the steel rod 1, and it is possible to save the trouble of introducing the pretension to the steel rod 1 in advance. Can be done. That is, according to the concrete pile manufacturing apparatus 100 provided with the inner formwork 20 composed of a pair of cores 21 and 22 that are close to each other by the cylinder device 40, the prestressed concrete pile can be easily manufactured. Can be done.
[0032]
　In the above embodiment, the pair of cores 21 and 22 are moved together by the cylinder device 40 so as to be drawn toward the center side of the manufacturing apparatus 100 so that the tips thereof are close to each other. The present invention is not limited to this, for example, one core 21 is fixed to the formwork 30 side, and the other core 22 is moved by the operation of the cylinder device 40 to be close to the one core 21. You may let it.
　Further, the cylinder device 40 is not limited to the tip side of the cores 21 and 22, and for example, the cylinder device 40 is provided at the rear end portion 21b of one core 21 and the piston rod 42 is provided at the rear end of the other core. The configuration may be such that the cores 22b are penetrated and connected, or cylinder devices are provided on the rear end portions 21b and 22b of the cores 21 and 22, respectively, and the cores 21 and 22 are pushed out toward the center of the device. It may be a configuration. Further, the tips of the cores 21 and 22 may be brought into contact with each other in advance and pressurized by the pump pressure at the time of putting concrete.
[0033]
　Further, in the present embodiment, the pretension is introduced into the steel rod 1 by disposing the cushioning material 50 between the joint metal fitting 2 and the formwork 30, but the joint metal fitting 2 and the formwork 30 When the cushioning material 50 is not arranged between them, tension may be applied to the steel rod 1 before the demolding of the inner form 20 to introduce the prestressed concrete into the concrete after the demolding.
[0034]
[Outline 2 of the embodiment]
　Further, various other embodiments based on the above embodiment will be described.
(1) When the drainage hole 62a is provided on the molded surface for molding the outer wall surface of the concrete pile, the portion thereof can be arbitrarily selected. As shown in FIG. 6, the drainage hole 62a may be provided on the plane having the largest area, even if it is not a corner portion. In this case as well, a water permeable filter that covers the drain hole 62a may be provided.
[0035]
(2) Further, as shown in FIG. 7, the formwork to be used may be provided with a drain hole 62a on the molding surface for molding the inner wall surface of the hollow portion of the concrete pile. In this case as well, a water permeable filter that covers the drain hole 62a may be provided. Since it is not necessary to provide the outer wall surface of the concrete pile on the forming surface to be formed, if the trace of the drainage hole 62a remains on the concrete surface, it can be prevented from being exposed to the outside.
　Without being bound by this, drainage holes 62a may be provided on both the molded surface for forming the outer wall surface of the concrete pile and the molded surface for forming the inner wall surface of the hollow portion of the concrete pile. Good drainage.
[0036]
(3) As shown in FIG. 8, a cylinder device or the like that slides a part 10A of the outer formwork body 10 with respect to another adjacent part 10B along a direction perpendicular to the axial direction of the pile forming space S. A manufacturing apparatus provided with the moving means 71 and capable of reducing and expanding the pile forming space S by the moving means 71 may be used. FIG. 8 shows an example in which the moving part 10A is used as the upper surface portion at the time of manufacturing, but the moving part may be used as one side surface portion at the time of manufacturing or both side surface portions at the time of manufacturing. It should be noted that the term "at the time of manufacture" is used only because it refers to the arrangement when the concrete piles are laid on their side.
　In addition, the mode of movement of the moving part 10A is also arbitrary, and by moving without tilting or moving while tilting, the cross section perpendicular to the axial direction of the concrete pile can be made into a square, a rectangle, a trapezoid, or the like. It may be made into a cross section such as a parallelogram. Further, by connecting the formwork members to each other with the hinge structure described later (FIGS. 26 and 27) together or independently, the cross-sectional shape can be deformed by the connecting angle of the hinge portion, and the cross-sectional shape can be easily made. Can be made separately.
[0037]
(4) Further, as shown in FIG. 9, a method of arranging the steel rods 1 dispersed in all directions around the axis of the pile forming space S may be implemented. For example, as shown in FIG. 9, the steel rod 1 may be limited to a total of four steel rods at the four corners so as to be embedded in the concrete pile. Since the number of steel rods 1 can be suppressed, the work time for arranging the steel rods 1 can be shortened.
[0038]
(5) On the other hand, as shown in FIG. 10, a larger number of steel rods 1 may be installed.
　It is assumed that the joint metal fitting 2 has a connection hole 2a of the steel rod 1, and two or more kinds of joint metal fittings having different numbers, arrangements, and inner diameters of one or more of the connection holes 2a are manufactured.
　Then, one type is selected from two or more types of joint hardware, and a steel rod corresponding to the selected joint hardware is selected and arranged.
　This makes it possible to easily select the diameter, number, and installation position of the steel rod 1.
[0039]
(6) Further, it is not necessary to use the entire length of the pile forming space S of the manufacturing apparatus 100.
　In the pile forming space S, a partition for partitioning the pile forming space S in the axial direction is installed at an arbitrary position in the axial direction, and concrete is poured into one side or both sides of the partition to form an axial length of the pile forming space S. It is possible to manufacture concrete piles of any length shorter than that.
　For example, as shown in FIG. 11, a set of a steel rod 1 and a pair of joint metal fittings 2 fixed to both ends thereof are installed in the range of the length La in the pile forming space S, and the others are set in the range of the length Lb. Another set of the steel rod 1 and the pair of joint hardware 2 fixed to both ends thereof is installed, and concrete is filled and molded. This makes it possible to manufacture a concrete pile having a length of La and a concrete pile having a length of Lb at the same time. If the joint hardware 2 functions sufficiently as a partition, this is applied as a partition. Other partition members may be inserted.
　Further, as shown in FIG. 12, by installing the mold box 80 in the space on one side where concrete is not put in (the part corresponding to length Lc), the space on the side where concrete is put in (the part corresponding to length Ld) is maintained. It can be done easily. In addition, in order to prevent the leakage of concrete, a seal member (81) for slidably sealing the cores 21 and 22 is appropriately provided.
　According to the above manufacturing method, concrete piles having different lengths can be manufactured with one formwork, and it is not necessary to prepare formwork having different lengths. It is also possible to manufacture multiple concrete piles at one time.
　Although FIGS. 11 and 12 describe the case where the pile forming space S is divided into two with one partition, the pile forming space S may be divided into three or more with two or more partitions. It is possible.
[0040]
(7) Slit-shaped drainage hole The
　above-mentioned drainage hole 62a can be used as a slit-shaped drainage hole (slit), and the same can be performed.
　FIG. 13 shows an example in which the drainage hole 62a provided in the perforated molded plate 62 described above has a slit shape.
　In the example shown in FIG. 13, the slit-shaped drainage hole 62a is formed long in the longitudinal direction (axial direction) at the center of the perforated molded plate 62. FIG. 14 shows a plan view.
　15 and 16 show other examples. In the example shown in FIG. 15, a plurality of slit-shaped drain holes 62a and 62a are provided in parallel. The number of parallels is arbitrary.
　The slit-shaped drainage hole 62a may be provided by dividing the drainage hole 62a into a plurality of parts in the longitudinal direction. In the example shown in FIG. 16, the slit-shaped drain holes 62a, 62a ... Are formed into three rows offset from each other next to each other, and are divided into a plurality of rows in the longitudinal direction.
　In the above configuration, one of the slit-shaped drain holes 62a is composed of one component.
　One of the slit-shaped drain holes 62a may be composed of two or more parts. For example, as shown in FIG. 17, a notch is provided in the side edge portion of the perforated molded plate 62, and a slit-shaped drain hole 62a is formed by a gap formed between the perforated molded plate 62 and the holding portion 61. can do. As described above, in the example of FIG. 17, the slit is divided into parts that can be divided in the width direction of the slit.
　By narrowing the width of the slit-shaped drainage hole 62a as described above, sufficient separability between concrete and water can be ensured without using the water permeable filter 63, and the device configuration and work can be simplified. Is.
　Further, by narrowing the width of the slit-shaped drainage hole 62a, a capillary phenomenon acts on the drainage hole 62a, whereby the drainage capacity is exhibited.
　By increasing the length of the slit-shaped drainage hole 62a, a large drainage hole area can be secured and a sufficient drainage capacity can be secured.
　If the slit-shaped drainage hole 62a is applied, the total area of ​​the drainage hole 62a for securing the required drainage capacity can be smaller because the capillary phenomenon acts as compared with the round hole as shown in FIG. .. The number of drainage holes 62a can be reduced not only because the total area is smaller than that of the round holes, but also because it can be formed longer in the axial direction, the number of drainage holes 62a can be significantly reduced as compared with the round holes. When the number and total area of ​​the drainage holes 62a are small, there is also an effect that cleaning work such as removing clogging of each of the drainage holes 62a is easy. Since the cleaning work is easy, the cleaning time is shortened and the next production can be performed at an early stage, so that one production cycle is shortened and the productivity is improved.
　Further, when one of the slit-shaped drain holes 62a is composed of two or more parts as described above, the cleaning work can be performed by disassembling the drainage holes 62a, so that the cleaning work is further easy. When the slit can be divided in the width direction of the slit, the inside of the slit is greatly opened by disassembly, so that the cleaning work is further facilitated.
[0041]
(8) Other manufacturing methods
　In the above-mentioned manufacturing method, the pretension (tensile stress) was introduced into the tension material at the same time as the compression molding of the concrete by the axial contraction of the pair of cores 21 and 22. However, there is also a method of performing before compression molding of concrete as follows.
　Therefore, the manufacturing apparatus shall have the following configurations in addition to the above configurations. 18-25 are top views.
　As shown in FIG. 18, the pair of formwork 30, 30 penetrates both ends of the tension material (steel rod 1) extending in the pile forming space S in the axial direction to the outside of the formwork 30. It shall have a hole 30b that allows it to extend to.
　As shown in FIG. 19 and the like, the first locking tools 91a, 92a, 91b, 92b for locking both ends of the tension material (steel rod 1) extending from the hole 30b to the pair of cores 21 and 22. As shown in FIG. 18 and the like, the tension material (steel rod 1) extending from the hole 30b is provided with second locking tools 93a and 93b for locking both ends of the tension material (steel rod 1) to the pair of formwork frames 30 and 30. do.
　The first locking tools 91a, 92a, 91b, 92b include flanges 91a, 91b fixed to the outer periphery of the ends of the cores 21 and 22, and nuts or wedge-type fasteners to be fastened to the tension material (steel rod 1). Fasteners 92a and 92b. As the second locking tools 93a and 93b, fasteners 93a and 93b such as nuts or wedge type fasteners to be fastened to the tension material (steel rod 1) are applied. The fasteners 92a, 92b, 93a, 93b are appropriately selected depending on the type of tension material. For those that cannot use screws, it is advisable to use friction type fasteners such as wedge type fasteners.
　The cushioning material 50 (see FIG. 1A) installed in the above-described embodiment is unnecessary in this embodiment. Further, as shown in FIG. 18, the portion of the tension material (steel rod 1) extending to the outside of the formwork 30 is required to be extended by adding other steel rods or the like using couplers 94a and 94b. The length may be secured (no coupler in FIGS. 20 to 25). The part that is not incorporated into the concrete pile can be shortened. The coupler and other steel rods used for extension can be used repeatedly, reducing unnecessary protrusions of the tension material (steel rod 1) to be cut, which will be described later, and reducing the manufacturing cost of concrete piles. Can be done.
[0042]
　Then, the manufacturing process is carried out as follows.
　As shown in FIG. 20, the outer formwork body 10 (excluding the upper lid portion 10u), the inner formwork 20 (see FIG. 1A), and the formwork 30 are assembled to form the four sides and the bottom surface of the pile forming space S, and the pile forming space is formed. A tension material (steel rod 1) extending in the axial direction of the pile forming space S is housed in S. The pair of joint hardware 2 described above is also housed in the pile forming space S if necessary, but the illustration is omitted. The formwork 30, 30 and the required number of tension members (steel rod 1) may be assembled in advance as shown in FIG.
　One of both ends of the tension material (steel rod 1) is locked to the core 21 by the first locking tools 91a and 92a, and the other is locked to the core 22 by the first locking tools 91b and 92b.
　As described above, after using the first locking tools 91a, 92a, 91b, 92b, the pair of cores 21 and 22 are extended in the axial direction by using the moving means (cylinder device 40) to form the pile forming space S. As it expands, it causes tensile stress in the tension material (steel rod 1). This state is shown in FIG.
　Next, the tension material (steel rod 1) is restrained in a state where tensile stress is generated by the outer form main body 10 and the formwork 30, 30. A second locking tool is used for this. As shown in FIG. 21, the fasteners 93a and 93b of the second locking tool are fastened to the tension material (steel rod 1), and the fasteners 93a and 93b are pressed against the outer surfaces of the formwork 30 and 30. Make it a state.
　Next, as shown in FIG. 22, concrete C is put into the pile forming space S.
　Next, as shown in FIG. 23, the fasteners 92a and 92b of the first locking tool are removed from the tension material (steel rod 1). Assemble the upper lid portion 10u of the outer form main body 10 and fasten the mold.
　The concrete molding step after this is the same as the above-mentioned manufacturing method. That is, as shown in FIG. 24, the pair of cores 21 and 22 are contracted in the axial direction using a moving means (cylinder device 40) to reduce the pile forming space S, and the concrete C is compression-formed. The water discharged from the concrete C by molding is drained from the drain hole 62a to the outside of the formwork, and the concrete C is hardened in a state where the tension material (steel rod 1) is held for a predetermined time to generate tensile stress. ..
　After the concrete C is hardened, the mold is removed as shown in FIG. 25, and the pressurized prestressed concrete pile PC1 is taken out. The formwork 30 and 30 can be removed by loosening the fasteners 93a and 93b, and the unnecessary protruding portion of the tension material (steel rod 1) is cut.
　According to the above manufacturing method, the pretension (tensile stress) to the tension material is independent of the concrete compression forming process while effectively utilizing the expansion and contraction function of the cores 21 and 22 to suppress the increase in the scale of the mechanical configuration. Since the introduction process can be performed, it is possible to manufacture a pressurized prestressed concrete pile having a desired pretension such as higher pretension. By utilizing the common mechanical function of expansion and contraction of the cores 21 and 22, the compressed state of concrete and the magnitude of pretension of the tension material can be controlled independently of each other.
[0043]
　In the above embodiments, the cross-sectional shape perpendicular to the axial direction of the outer mold body 10 is rectangular, and the cross-sectional shape perpendicular to the axial direction of the pile forming space S is octagonal, but the present invention is limited thereto. The cross-sectional shape is arbitrary. For example, the cross-sectional shape of the outer form main body 10 may be circular, that is, the pile forming space S may be cylindrical, and the perforated forming plate may be an arc-shaped plate that fits into a part of the outer peripheral surface of the cylinder. Similarly, the cross-sectional shape of the cores 21 and 22 is arbitrary.
　Further, the technique of the present invention is not limited to manufacturing PC piles as concrete piles, but can also be applied to manufacturing reinforced concrete piles (RC piles) by applying reinforcing bars as reinforcing materials.
[0044]
　In the above embodiment, the slit-shaped drainage hole 62a is formed between the perforated molded plate 62 or the perforated molded plate 62 and the holding portion 61, but the slit-shaped drainage hole 62a is also formed in the outer mold body 10 and the inner mold. It can be provided in various places such as the frame 20 and the slit form 30.
　As shown in FIGS. 26 and 27, the gap between the bottom surface portion 10b of the outer form main body 10 and the side surface portions 10L and 10R may be a slit-shaped drain hole 62a.
　In this case, the bottom formwork member 10b and the side surface formwork members 10L and 10R are opened and closed by hinge connection, and when the formwork is fastened as shown in FIG. 27, the slit-shaped drainage hole 62a has a predetermined gap size. It can be made to function as a drainage hole. The slit-shaped drainage hole 62a in this case is continuous with a predetermined dimension in the axial direction. The portion where the slit is not provided may have a structure in which the members are in contact with each other. Further, when the mold is opened as shown in FIG. 26, the inside of the slit-shaped drainage hole 62a is also wide open, so that cleaning becomes easy. Special parts for providing drainage holes such as the perforated molded plate 62 are not required, and the formwork configuration is simplified.
　Although not shown, a gap may be provided between the upper lid portion 10u and the side surface portions 10L and 10R to form a slit-shaped drainage hole. In that case, the same can be performed by hinge-connecting the upper lid portion 10u and one side surface portion 10L or 10R so that the upper lid portion 10u can be opened and closed.
　Further, the connection between the constituent parts of the outer formwork 10 such as the upper lid portion 10u, the side surface portions 10L, 10R, and the bottom surface portion 10b does not have to be a hinge connection. When the outer mold 10 is assembled and fastened, a gap may remain between the adjacent components in a slit shape, and this gap may be a slit-shaped drain hole 62a.
Industrial applicability
[0045]
　The present invention can be used for manufacturing concrete piles.
Code description
[0046]
1 Steel rod
2 Joint hardware
2a Connection hole
10 Outer formwork Main body
20 Inner formwork
21, 22 Core
30 Filling formwork
40 Cylinder device
41 Cylinder tube
42 Piston rod
43 Connecting pin
50 Buffer material
60 Outer formwork Drainage part
61 Holding Part
62 Perforated forming plate
62a Drainage hole
63 Water permeation filter
64 Magnet
71 Transportation means
100 Manufacturing equipment
S Pile forming space
The scope of the claims
[Request item 1]
　Using a formwork that has a drainage hole that communicates with the outside on the molding surface and can reduce and expand the
　pile forming space, concrete is put into the pile forming space, and the concrete is reduced by reducing the pile forming space. A method for manufacturing a concrete pile which is compression-molded, drains water discharged from the concrete by the compression molding from the drain hole to the outside of the formwork, and is held for a predetermined time to harden the concrete.
[Request item 2]
　The concrete pile according to claim 1, wherein a water permeable filter that filters and separates water from concrete so as to cover the drainage hole is installed on the molded surface provided with the drainage hole, and then concrete is put into the pile forming space. Production method.
[Request Item 3]
　The method for manufacturing a concrete pile according to claim 1 or 2, wherein the formwork is provided with the drainage hole on the molding surface for forming the outer wall surface of the concrete pile.
[Request Item 4]
　The method for manufacturing a concrete pile according to claim 3, wherein the formwork is dispersed in all directions around the axis of the pile forming space and the drain holes are provided.
[Request Item 5]
　The method for manufacturing a concrete pile according to any one of claims 1 to 4, wherein the formwork is provided with the drainage hole on the molding surface for forming the inner wall surface of the hollow portion of the concrete pile.
[Request Item 6]
　The method for manufacturing a concrete pile according to any one of claims 1 to 5, wherein the drainage hole has a shape extending outward from an open end on a molded surface.
[Request Item 7]
　The concrete pile according to any one of claims 1 to 6, wherein the formwork has the drainage hole and a removable perforated molding plate constituting the molding surface of the portion where the drainage hole is provided. Manufacturing method.
[Request Item 8]
　The formwork has an outer formwork for forming the outer wall surface of the concrete pile, an inner formwork for forming the inner wall surface of the hollow portion of the concrete pile, and a pair of formwork for forming the upper and lower end surfaces of the concrete pile. The method for manufacturing a concrete pile according to any one of claims 1 to 7.
[Request Item 9]

　The inner formwork has a tapered surface whose diameter is reduced toward the tip along the axial direction of the pile forming space, and is composed of a pair of cores in which the 　tips are arranged facing each other. The frame slidably supports the rear ends of the
　pair of cores, and at least one of the cores slides along the axial direction so that the tips of the pair of cores are separated from each other in close proximity to each other. The method for manufacturing a concrete pile according to claim 8, wherein the moving means is used to reduce and expand the pile forming space by the moving means.
[Request Item 10]
　A moving means for sliding a part of the outer formwork with respect to another adjacent part along a direction perpendicular to the axial direction of the pile forming space is used, and the pile forming space is reduced and expanded by the moving means. The method for manufacturing a concrete pile according to claim 8 or 9.
[Request Item 11]
　The method for manufacturing a concrete pile according to any one of claims 1 to 10, wherein the reinforcing material is stored in the pile forming space and the concrete is compression-formed.
[Request Item 12]
　From claim 1, the concrete is compression-formed by accommodating a tension material extending in the axial direction of the pile forming space and a pair of joint hardware fixed to both ends of the tension material in the pile forming space. The method for manufacturing a concrete pile according to any one of claims 11.
[Request Item 13]
　The method for manufacturing a concrete pile according to claim 12, wherein the tension material is dispersed in all directions around the axis of the pile forming space.
[Request Item 14]
　The method for manufacturing a concrete pile according to claim 12 or 13, wherein the concrete is hardened in a state where tensile stress is generated in the tension material.
[Request Item 15]
　The joint hardware has connection holes for the tension material,
　and two or more types of the joint hardware having different numbers, arrangements, and inner diameters of one or more of the connection holes are manufactured, and the
　two or more types of joint hardware are manufactured. The method for manufacturing a concrete pile according to any one of claims 12 to 14, wherein one type is selected from the above and the tension member is arranged corresponding to the selected joint hardware.
[Request 16]
　In the pile forming space, a partition that partitions the pile forming space in the axial direction is installed at an arbitrary position in the axial direction, and concrete is poured into one side or both sides of the partition to form an axial length of the pile forming space. The method for manufacturing a concrete pile according to any one of claims 1 to 15, wherein a concrete pile having an arbitrary length shorter than that of the pile is manufactured.
[Request Item 17]
　The method for manufacturing a concrete pile according to claim 1, wherein the drainage hole has a slit shape.
[Request Item 18]
　A tension material extending in the axial direction of the pile forming space is housed in the pile forming space,
　one of both ends of the tensioning material is locked to one of the pair of cores, and both ends of the tensioning material are engaged. The other of the portions is locked to the other of the pair of cores, and the
　pair of cores is extended in the axial direction by using the moving means to expand the pile forming space and to the tension material. Tensile stress is generated, the
　tension material is restrained in the state where the tensile stress is generated by the outer formwork and the formwork
　, concrete is put into the pile forming space, and the pair is used by the moving means. The core is contracted in the axial direction to shrink the pile forming space to compression-mold the concrete, and the water discharged from the concrete by the compression molding is drained from the drain hole to the outside of the formwork. The method for manufacturing a concrete pile according to claim 9, wherein the concrete is hardened in a state where the tension material is held for a predetermined time and a tensile stress is generated in the tension material.
[Request 19]
　A concrete pile manufacturing device equipped with a formwork for compression-forming a concrete pile,
　wherein a drain hole communicating with the outside is provided on the forming surface of the formwork, and the
　formwork is used for compression-forming the concrete pile. A concrete pile manufacturing device that makes it possible to reduce and expand the pile forming space.
[Request 20]
　The concrete pile manufacturing apparatus according to claim 19, wherein a water permeable filter is installed on a molded surface provided with the drainage hole so as to cover the drainage hole.
[Request 21]
　The concrete pile manufacturing apparatus according to claim 19 or 20, wherein the formwork is provided with the drainage hole on the molding surface for forming the outer wall surface of the concrete pile.
[Request 22]
　The concrete pile manufacturing apparatus according to claim 21, wherein the formwork is dispersed in all directions around the axis of the pile forming space and the drain holes are provided.
[Request 23]
　The concrete pile manufacturing apparatus according to any one of claims 19 to 22, wherein the formwork is provided with the drainage hole on the molding surface for forming the inner wall surface of the hollow portion of the concrete pile.
[Request 24]
　The concrete pile manufacturing apparatus according to any one of claims 19 to 23, wherein the drainage hole has a shape extending outward from an open end on a molding surface.
[Request 25]
　The concrete pile according to any one of claims 19 to 24, wherein the formwork has the drainage hole and a removable perforated molding plate constituting the molding surface of the portion where the drainage hole is provided. Manufacturing equipment.
[Request 26]
　The formwork has an outer formwork for forming the outer wall surface of the concrete pile, an inner formwork for forming the inner wall surface of the hollow portion of the concrete pile, and a pair of formwork for forming the upper and lower end surfaces of the concrete pile. 19. The concrete pile manufacturing apparatus according to any one of claims 25.
[Request 27]

　The inner formwork 　has a tapered surface whose diameter is reduced toward the tip along the axial direction of the pile forming space, and is composed of a pair of cores in which the tips thereof are arranged facing each other. , The rear end of the pair of cores is slidably supported,
　and at least one of the cores is slid along the axial direction so that the tips of the pair of cores are separated from each other in close proximity to each other. The concrete pile manufacturing apparatus according to claim 26, which comprises a moving means for causing the pile forming space to be reduced or expanded by the moving means.
[Request 28]
　A moving means for sliding a part of the outer formwork with respect to another adjacent portion along a direction perpendicular to the axial direction of the pile forming space is provided, and the pile forming space is reduced and expanded by the moving means. The concrete pile manufacturing apparatus according to claim 26 or 27, which is made possible.
[Request 29]
　The concrete pile according to any one of claims 26 to 28, wherein the outer formwork is composed of a plurality of constituent parts, and the drainage hole is formed by a gap between the adjacent constituent parts at the time of molding. manufacturing device.
[Request Item 30]
　The concrete pile manufacturing apparatus according to claim 29, wherein the plurality of components are hinged to each other.
[Request 31]
　The concrete pile manufacturing apparatus according to claim 19, wherein the drainage hole has a slit shape.
[Request Item 32]
　The pair of formwork has holes that allow both ends of the tension material extending in the axial direction to penetrate the pile forming space and extend to the outside of the formwork
　. A first locking tool that locks both ends of the tension material extending from the portion to the pair of cores, and both ends of the tension material extending from the hole portion are locked to the pair of stake formwork. A second locking tool is provided, and
　after using the first locking tool, the pair of cores is extended in the axial direction by using the moving means to expand the pile forming space and the tension. It is possible to generate tensile stress in the material, and it
　is possible to restrain the tension material in the state where the tensile stress is generated by the outer formwork and the stake formwork by using the second locking tool. 27. The concrete pile manufacturing apparatus according to claim 27.