Hole forming form

Abstract

To provide an easily assembled hole forming formwork capable of forming a hole having irregularities along an axial direction in a concrete molded body.SOLUTION: A hole forming formwork 1 for forming a hole 3 in a concrete molded body 2 having irregularities along an axial direction on at least a part of a circumferential direction comprises: a core body 16 extending along the axial direction; and a plurality of divided frame bodies 17 extending along the axial direction and arranged while spaced apart in a predetermined first direction perpendicular to the axial direction so as to sandwich the core body. Each of the plurality of divided frame bodies has a first outer peripheral surface 20 that forms a first part of an inner peripheral surface of the hole that includes irregularities and a plurality of projection parts 22 that project outward from the first outer peripheral surface to form the irregularities. The core body is movable in the axial direction relative to the divided frame body.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a hole forming form for forming holes in a concrete molded body. [Background technology]

[0002] Conventionally, a concrete molded body formed by pouring concrete into a formwork may have holes for inserting reinforcing bars or the like. After the reinforcing bars or the like are inserted into the holes, a filler material such as non-shrink grout is injected. When the filler material solidifies, the reinforcing bars or the like inserted into the holes are fixed to the concrete molded body via the filler material. In order to improve the fixing force of the reinforcing bars or the like inserted into the holes to the concrete molded body, the inner surface of the holes may be provided with irregularities.

[0003] Patent Document 1 discloses a hole-forming form for forming holes in a concrete molded body. The hole-forming member has a core pipe (core body) and a belt wound around the core pipe. The outer surface of the belt is provided with ridges (projections). As a result, when the belt is wound around the core pipe, the outer peripheral surface of the hole-forming form is uneven. After the hole-forming form is placed in the form for the concrete molded body, concrete in a fluid state is poured into the form. As the poured concrete solidifies, a hole is formed having an inner surface with an uneven shape corresponding to the uneven shape of the hole-forming form. After the concrete solidifies, the core pipe is removed from the concrete molded body, and then the end of the belt is pulled to pull the hole-forming form out of the hole formed in the concrete molded body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-035524 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the hole forming member of Patent Document 1, the belt contacts the concrete, and is deteriorated by repeated extraction from the hole formed in the concrete compact. Therefore, the belt needs to be replaced when the hole forming form is used repeatedly. In addition, the belt needs to be wound around the core pipe to assemble the hole forming form, and the task of winding the belt around the core pipe takes time.

[0006] In view of the above background, an object of the present invention is to provide a hole forming formwork that is easy to assemble and can form a hole having projections and recesses along the axial direction in a concrete molded body. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a hole forming formwork (1) for forming a hole (3) in a concrete molded body (2) having an axially-oriented irregularity on at least a portion of the circumferential direction, the formwork comprising a core body (16) extending along the axial direction, and a plurality of divided frame bodies (17) extending along the axial direction and arranged at a distance in a predetermined first direction perpendicular to the axial direction so as to sandwich the core body, each of the plurality of divided frame bodies having a first outer peripheral surface (20) forming a first portion of the inner peripheral surface of the hole including the irregularity, and a plurality of convex portions (22) protruding outward from the first outer peripheral surface to form the irregularity, and the core body is movable in the axial direction relative to the divided frame bodies.

[0008] According to this embodiment, a hole having projections and recesses along the axial direction is formed in the concrete molded body. When the core body is removed from the concrete molded body, a space is formed inside the hole forming form. By moving each divided frame body toward this space, the projections on each divided frame body are released from the projections on the concrete molded body, and each divided frame body can be moved in the direction of removal from the concrete molded body. The hole forming formwork is assembled by clamping each divided frame body to the core body, which makes it easy to assemble the hole forming formwork.

[0009] In the above aspect, the core may further include two second outer peripheral surfaces (27) which cooperate with the first outer peripheral surface to form the inner peripheral surface of the hole and are smooth along the axial direction, and each of the two second outer peripheral surfaces may form a surface of the core body facing each other in a second direction which intersects with the first direction.

[0010] According to this embodiment, when the core body is extracted from the concrete molded body, a space is formed inside the hole forming form in which each of the divided frame bodies can move in the first direction. As a result, by moving each of the divided frame bodies toward this space, the protrusions on each of the divided frame bodies are released from the recesses and projections on the concrete molded body, and each of the divided frame bodies can be moved in the direction of being extracted from the concrete molded body.

[0011] In the above aspect, the two second outer peripheral surfaces are parallel to each other in a side view, the core body has a first core body (16A) and a second core body (16B) extending along the axial direction and including corresponding second outer peripheral surfaces, a first surface (28) of the first core body which forms the back surface of the second outer peripheral surface of the first core body and a second surface (29) of the second core body which forms the back surface of the second outer peripheral surface of the second core body abut each other, and the first surface and the second surface are preferably formed smoothly along the axial direction.

[0012] According to this embodiment, the two second outer peripheral surfaces are individually peeled off from the inner peripheral surfaces of the corresponding holes, so that the force required to extract the first core and the second core from the concrete molded body is reduced.

[0013] In the above aspect, the two second outer peripheral surfaces are parallel to each other in a side view, the core body has a first core body (16A) and a second core body (16B) extending along the axial direction and including corresponding second outer peripheral surfaces, the first core body has at least one first protrusion (30) protruding from the back side of the second outer peripheral surface toward the second core body, and the second core body has at least one second protrusion (31) protruding from the back side of the second outer peripheral surface toward the first core body and abutting the first protrusion, and each of a first surface (28) of the first protrusion abutting the second protrusion and a second surface (29) of the second protrusion abutting the first surface is preferably formed smoothly along the axial direction.

[0014] According to this aspect, since each core body is light in weight, the force required to remove each core body is small.

[0015] In the above aspect, the first surface and the second surface may be inclined with respect to the two second outer peripheral surfaces in a side view.

[0016] According to this aspect, one core body is extracted from the concrete molded body along the other inclined surface, so that one core body can be extracted with the second outer peripheral surface of the one core body peeled off from the inner peripheral surface of the corresponding hole.

[0017] In the above aspect, the core body may have a hollow support portion (33) extending along the axial direction, two main body portions (34) held by the support portion so as to be movable in the second direction and including corresponding second outer circumferential surfaces, and an expansion portion (35) arranged between the two main body portions and expandable at least in the second direction.

[0018] According to this aspect, the expansion portion allows the two main bodies to move in a direction away from each other or in a direction toward each other. By moving the two main bodies in a direction toward each other, the core is extracted from the concrete molded body with the second outer circumferential surface peeled off from the inner circumferential surface of the corresponding hole.

[0019] In the above aspect, the frame may further include two second outer peripheral surfaces (27) which cooperate with the first outer peripheral surface to form the inner peripheral surface of the hole, and two retaining bodies (45) which extend along the axial direction and include corresponding second outer peripheral surfaces, each of the two retaining bodies being arranged spaced apart in a second direction intersecting the first direction so as to sandwich the core body, and being movable in the second direction relative to the split frame body.

[0020] According to this aspect, when the core body is extracted from the concrete molded body, a space is formed inside the hole forming form in which each retainer can move in the second direction. By extracting the core body and each retainer from the concrete molded body, the space formed inside the hole forming form is expanded, and each divided frame body can be moved in the first direction. By moving each divided frame body toward this space, the protrusions on each divided frame body are released from the engagement with the concaves and convexes on the concrete molded body, and each divided frame body can be moved in the direction of extraction from the concrete molded body.

[0021] In the above aspect, the holder may be formed in a tapered shape that becomes wider from the second outer circumferential surface toward the core body.

[0022] According to this embodiment, when each retaining body is removed from the concrete molded body, the movement of each retaining body in the second direction becomes easy.

[0023] In the above aspect, it is preferable that there are two split frames, the core body is a tube having a rectangular cross section, and four corners (49) abut against the corresponding split frames and the holder.

[0024] According to this embodiment, the core body can be easily extracted from the concrete molded body.

[0025] In the above aspect, the second outer circumferential surface may be formed smoothly along the axial direction.

[0026] According to this embodiment, the concrete molded body can be removed without moving the second outer peripheral surface in the first direction.

[0027] In the above aspect, the core body may have a plurality of step surfaces (26) extending in the axial direction and the second direction in portions of the core body that are sandwiched between the plurality of split frame bodies.

[0028] According to this aspect, after the hole forming form is placed at a predetermined position, the separate frame bodies are prevented from moving in the second direction.

[0029] In the above aspect, the first outer peripheral surface has an arc shape when viewed in a cross section perpendicular to the axial direction, and when viewed in the cross section, the dimension (L2) of the first outer peripheral surface in the second direction is set to be less than or equal to the dimensions (L1, L3) of the two second outer peripheral surfaces in the second direction.

[0030] According to this aspect, each split frame can be slid in the first direction, and the entire first outer peripheral surface can be peeled off from the inner peripheral surface of the hole without rotating the split frame.

[0031] In the above aspect, the multiple convex portions form circumferentially extending protrusions (23), and in a portion near the circumferential end of the first outer peripheral surface, the radial dimension of the protrusions is preferably smaller the closer it is to the circumferential end.

[0032] According to this embodiment, the separate frames can be easily slid in the first direction.

[0033] In the above aspect, it is preferable that at least one end of the core body in the axial direction be provided with a first locking portion (25) for locking a jig for pulling out the core body in the axial direction.

[0034] According to this embodiment, the operation of extracting the core from the concrete molded body can be carried out efficiently.

[0035] In the above aspect, the hole forming formwork may have a tubular member (46) that forms a passage for filler material from the outer surface of the concrete body to the hole, and a recess (47) that receives the end of the tubular member.

[0036] According to this embodiment, it is possible to form injection and discharge holes for filling the holes formed in the concrete molded body with a filler. Effect of the Invention

[0037] The present invention can provide a hole forming formwork that can be easily assembled and that can form a hole having projections and recesses along the axial direction in a concrete body. [Brief description of the drawings]

[0038] [Figure 1] FIG. 13 is a diagram showing an example of use of a hole formed by the hole forming form according to the present embodiment. [Diagram 2] FIG. 1 is a perspective view showing a hole forming form according to a first embodiment; [Diagram 3] FIG. 1 is an exploded perspective view showing a hole forming form according to a first embodiment; [Figure 4] FIG. 4 is a front cross-sectional view showing the hole forming form according to the first embodiment (cross-sectional view taken along the line IV-IV in FIG. 2). [Diagram 5] FIG. 13 is an exploded perspective view showing a hole forming form according to a second embodiment. [Figure 6] FIG. 11 is a side view showing a core body according to a second embodiment. [Figure 7] FIG. 13 is a side view showing the core body according to the third embodiment. [Figure 8] FIG. 13 is an exploded perspective view showing a hole forming form according to a fourth embodiment. [Figure 9] FIG. 13 is a front cross-sectional view showing a hole forming form according to a fourth embodiment. [Figure 10] FIG. 13 is a front cross-sectional view showing a hole forming form according to a fourth embodiment. [Figure 11] FIG. 13 is a perspective view showing a hole forming form according to a fifth embodiment. [Figure 12] FIG. 13 is an exploded perspective view showing a hole forming form according to a fifth embodiment. [Figure 13]13 is a front cross-sectional view showing a hole forming form according to a fifth embodiment (cross-sectional view taken along XIII-XIII in FIG. 12 ). [Figure 14] FIG. 13 is an exploded cross-sectional view showing a hole forming form according to the sixth embodiment. [Figure 15] FIG. 13 is a front cross-sectional view showing a hole forming form according to the seventh embodiment. [Figure 16] FIG. 13 is an exploded cross-sectional view showing a hole forming form according to an eighth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] (First embodiment) Hereinafter, several embodiments of the hole forming formwork 1 according to the present invention will be described with reference to the drawings. The hole forming formwork 1 (see FIG. 2) is a formwork for forming a hole 3 in a concrete molded body 2. The concrete molded body 2 is formed by pouring concrete with the hole forming formwork 1 placed at a predetermined position in a formwork for molding the concrete molded body 2 and hardening the concrete. Thereafter, the hole forming formwork 1 is removed from the concrete molded body 2, thereby forming a hole 3 in the concrete molded body 2. The inner peripheral surface of the hole 3 provided in the concrete molded body 2 is formed into a shape that matches the shape of the outer peripheral surface of the hole forming formwork 1.

[0040] In this embodiment, an example will be described in which a hole 3 extending horizontally is formed in a concrete molded body 2 by a hole forming formwork 1, but the extending direction of the hole 3 is not particularly limited. In the following description, the horizontal direction in which the hole 3 extends is defined as the front-rear direction, and the left-right and up-down directions are defined.

[0041] As shown in Fig. 1, holes 3 are provided in a concrete molded body 2, i.e., a precast concrete member. Specifically, a plurality of holes 3 are provided so as to be continuous with a column member 6 forming a column and one of two beam members 8 forming a beam. In this embodiment, four holes 3 are provided, arranged in two rows in each of the vertical and horizontal directions. Hole 3A provided in the column member 6 penetrates the column member 6 in the front-rear direction.

[0042] The beam member 8 has a first beam member 8A arranged in front of the column member 6 and a second beam member 8B arranged behind the column member 6. Four holes 3B are provided in the first beam member 8A arranged in front of the column member 6. Four tubular mechanical joints 10 extending in the front-rear direction are embedded in the first beam member 8A in a state in which they are arranged in two rows in each of the up-down direction and the left-right direction. The holes 3B provided in the first beam member 8A are provided so as to communicate the inside of the corresponding mechanical joint 10 with the outside. In addition, the first beam member 8A is provided with a plurality of inlet and outlet holes 13 extending in the up-down direction. Each of the plurality of inlet and outlet holes 13 is provided so as to communicate the inside of each of the corresponding upper and lower mechanical joints 10 with the outside.

[0043] The second beam member 8B arranged behind the column member 6 is provided with four reinforcing bars 12 protruding forward, arranged in two rows in each of the vertical and horizontal directions.

[0044] Each of the multiple holes 3B provided in the first beam member 8A is aligned with the corresponding hole 3A provided in the column member 6 and the corresponding reinforcing bar 12 provided in the second beam member 8B. That is, when the front surface of the column member 6 and the rear surface of the first beam member 8A are opposed to each other through a joint (gap), and the rear surface of the column member 6 and the front surface of the second beam member 8B are opposed to each other through a joint, each of the multiple reinforcing bars 12 is received in the corresponding hole 3 and inside the mechanical joint 10. In this state, a filler material (not shown), such as non-shrink grout, is injected from the joint, so that the filler material is filled in the joint, the hole 3, and the inside of the mechanical joint 10. When the filler material hardens, each of the multiple reinforcing bars 12 is fixed to the first beam member 8A and the column member 6 through the filler material.

[0045] These holes 3A, 3B have unevenness along the axial direction at least in a part of the circumferential direction in order to firmly fix the reinforcing bars 12 to the column member 6 and the first beam member 8A. The holes 3A, 3B are formed using a hole forming formwork 1 (FIG. 2) when the column member 6 and the first beam member 8A are formed.

[0046] 2 and 3, the hole forming formwork 1 for forming a hole 3 in a concrete molded body 2 has a core body 16 extending along the front-rear direction which is the axial direction of the hole 3, and two separate frame bodies 17 extending along the front-rear direction and arranged to sandwich the core body 16. The core body 16 and each separate frame body 17 are preferably made of a material with a high elastic modulus, such as hard resin or steel. Each of the two separate frame bodies 17 extends in the front-rear direction and is arranged spaced apart from each other in the left-right direction (first direction) perpendicular to the front-rear direction.

[0047] As also shown in Fig. 4, each of the two divided frame bodies 17 has an arc shape in a front cross section seen from the front-rear direction. Each divided frame body 17 may be formed from two side members obtained by dividing a cylindrical member into three parts on the left and right. Alternatively, each divided frame body 17 may be formed by curving each of two plate-like members outwardly to the left and right. Each of the outer peripheral surfaces of the two divided frame bodies 17 forms a first outer peripheral surface 20 that forms a first portion that forms a part of the circumferential direction of the inner peripheral surface of the hole 3.

[0048] Each of the two divided frames 17 has a plurality of protrusions 22 that protrude outward from the first outer peripheral surface 20 to form projections and recesses. In this embodiment, the plurality of protrusions 22 form ridges 23 that extend in the circumferential direction of the first outer peripheral surface 20. As a result, the first outer peripheral surface 20 forms projections and recesses along the axial direction. In a portion close to the upper circumferential end of the first outer peripheral surface 20, the radial dimension of the ridges 23 becomes smaller the closer to the upper circumferential end. In a portion close to the lower circumferential end of the first outer peripheral surface 20, the radial dimension of the ridges 23 becomes smaller the closer to the lower circumferential end.

[0049] The surfaces of the upper and lower circumferential end portions of each divided frame 17 face inwardly to the left and right and are formed smoothly along the front-rear direction. The surfaces of the upper and lower circumferential end portions of each divided frame 17 form abutment surfaces that abut against corresponding side surfaces of the core body 16, which will be described later.

[0050] The core body 16 is formed from a plate-like member that is long in the up-down direction (second direction) in a front cross-sectional view seen from the front. That is, the core body 16 has an upper surface and a lower surface that extend in the front-rear direction and the left-right direction, and left and right side surfaces that extend in the front-rear direction and the up-down direction. The upper surface, lower surface, and left and right side surfaces of the core body 16 are each formed smoothly along the front-rear direction. The upper surface and lower surface of the core body 16 are parallel to each other.

[0051] The left and right side surfaces of the upper and lower parts of the core body 16 form portions that come into contact with the corresponding surfaces of the upper and lower circumferential ends of each of the divided frames 17. The left and right side surfaces of the upper and lower parts of the core body 16 are located left and right inward from the left and right side surfaces of the center part of the core body 16. In other words, the core body 16 has a plurality of step surfaces 26 that connect the left and right side surfaces of the upper and lower parts to the corresponding left and right side surfaces of the center part. The step surfaces 26 extend in the front-rear and up-down directions.

[0052] A through hole 24 (FIGS. 1 and 2) penetrating in the left-right direction is provided in the vertical center of the front end of the core body 16. The through hole 24 forms a first locking portion 25 that locks a jig (not shown) for pulling out the core body 16 in the front-rear direction, which will be described later.

[0053] The vertical width dimension L1 from the upper surface to the lower surface of the core body 16 is set to be equal to or larger than the vertical width dimension L2 from the upper end to the lower end of each divided frame body 17. In this embodiment, the length of the chord from the upper end to the lower end of the divided frame body 17 corresponds to the vertical width dimension L2 from the upper end to the lower end of the divided frame body 17.

[0054] The faces of the upper and lower circumferential ends of the left split frame 17 abut against the left side surfaces of the corresponding upper and lower parts of the core body 16. The faces of the upper and lower circumferential ends of the right split frame 17 abut against the right side surfaces of the corresponding upper and lower parts of the core body 16. As a result, each split frame 17 is arranged to hold the core body 16 in the left-right direction. Since all of these abutting surfaces are smooth in the front-to-rear direction, the core body 16 is able to move in the front-to-rear direction relative to the split frame 17.

[0055] When each divided frame 17 is arranged to sandwich the core body 16, the upper and lower surfaces of the core body 16 as well as the first outer peripheral surface 20 form the outer peripheral surface of the hole forming formwork 1. That is, the upper and lower surfaces of the core body 16 form a second outer peripheral surface 27 that cooperates with the first outer peripheral surface 20 of the divided frame 17 to form the inner peripheral surface of the hole 3. When the hole forming formwork 1 is arranged at a predetermined position in the formwork for molding the concrete molded body 2, a tape or the like (not shown) is attached in advance in the circumferential direction of the hole forming formwork 1, so that each divided frame 17 is held in a state of sandwiching the core body 16.

[0056] To remove the hole forming form 1 from the concrete molded body 2, an operator first removes the core body 16 from the concrete molded body 2, and then sequentially removes each of the two divided frames 17 from the concrete molded body 2. A tool (not shown), such as a slide hammer, may be used to remove the core body 16. The core body 16 and the tool (such as a slide hammer) may be connected by engaging a jig (not shown), such as a shackle, with a first engaging portion 25 provided on the core body 16. This causes the core body 16 to move forward relative to the divided frames 17, and the core body 16 is removed from the concrete molded body 2.

[0057] By removing the core body 16 from the concrete molded body 2, a space is formed inside the hole forming form 1. Then, the worker slides one of the divided frames 17 inwardly to the left and right toward the space formed inside the hole forming form 1. As a result, the first outer peripheral surface 20 of the divided frame 17 is peeled off from the inner peripheral surface of the corresponding hole 3, and each of the tips of the multiple protrusions 23 moves inwardly to the left and right from the tips of the convex parts formed on the inner peripheral surface of the hole 3. Then, the worker further moves one of the divided frames 17 forward, so that one of the divided frames 17 is removed from the concrete molded body 2. Then, the worker further removes the other divided frame 17 from the concrete molded body 2 in the same procedure as the removal of one of the divided frames 17 from the concrete molded body 2. As a result, the hole forming form 1 is removed from the concrete molded body 2.

[0058] By moving each of the divided frames 17 toward the space formed inside the hole forming form 1, the protrusions 23 (protrusions 22) on each of the divided frames 17 are released from the unevenness on the concrete molded body 2. This allows each of the divided frames 17 to be moved in the direction of being removed from the concrete molded body 2.

[0059] The hole forming formwork 1 is assembled by clamping each divided frame 17 to the core body 16, so that the hole forming formwork 1 can be easily assembled. As shown in Figs. 2 to 4, the core body 16 has a plurality of step surfaces 26 connecting the left and right side surfaces of the upper and lower parts with the corresponding left and right side surfaces of the center part. As a result, when each divided frame body 17 clamps the core body 16, the step surfaces 26 suppress excessive movement of each divided frame body 17 in the vertical direction. Therefore, after the hole forming formwork 1 is placed at a predetermined position in the formwork for molding the concrete molded body 2, each divided frame body 17 is suppressed from moving in the vertical direction.

[0060] The upper and lower surfaces of the core 16 each form a second outer peripheral surface 27 that cooperates with the first outer peripheral surface 20 to form the inner peripheral surface of the hole 3, and are formed smoothly along the front-to-rear direction. This makes it possible for the core 16 to slip out of the concrete molded body 2 even when the second outer peripheral surface 27 is attached to the inner peripheral surface of the hole 3.

[0061] The vertical width dimension L1 from the upper surface to the lower surface of core body 16 is set to be equal to or larger than the vertical width dimension L2 from the upper end to the lower end of split frame body 17. This allows each split frame body 17 to slide left and right, and the entire first outer peripheral surface 20 can be peeled off from the inner peripheral surface of hole 3 without rotating split frame body 17.

[0062] The radial dimension of the protrusions 23 near the upper and lower circumferential ends of each split frame 17 is smaller as they approach the corresponding end. This makes it easier for the split frame 17 to move inwardly to the left and right toward the space formed inside the hole forming form 1.

[0063] A through hole 24 forming a first locking portion 25 for locking a jig is provided in the vertical center of the front end of the core body 16. This allows the core body 16 to be extracted from the concrete molded body 2 using an appropriate tool. Therefore, the work of extracting the core body 16 from the concrete molded body 2 can be performed efficiently.

[0064] Second embodiment Next, a second embodiment of the present invention will be described with reference to Figures 5 and 6. Elements that are the same as or similar to those in the first embodiment are given the same reference numerals, and duplicated explanations will be omitted. In the hole forming form 1 of this embodiment, the configuration of the core body 16 is different from that of the first embodiment, and the other configurations (the configurations of the split frame bodies 17) are the same as those of the first embodiment. Below, the differences from the first embodiment will be described.

[0065] The core body 16 has a first core body 16A and a second core body 16B extending along the front-rear direction. The first core body 16A and the second core body 16B are formed by dividing the core body 16 of the first embodiment into two parts, upper and lower. The upper surface of the first core body 16A forms the upper second outer peripheral surface 27. The lower surface of the first core body 16A (hereinafter referred to as the first surface 28) forms the back surface of the second outer peripheral surface 27 of the first core body 16A. The lower surface of the second core body 16B forms the lower second outer peripheral surface 27. The upper surface of the second core body 16B (hereinafter referred to as the second surface 29) forms the back surface of the second outer peripheral surface 27 of the second core body 16B. The first surface 28 and the second surface 29 are in contact with each other.

[0066] The first surface 28 and the second surface 29 are formed smoothly along the front-rear direction. The first surface 28 and the second surface 29 are inclined with respect to the two second outer peripheral surfaces 27 in a side view. Specifically, the height from the upper surface of the first core body 16A to the first surface 28 decreases toward the rear. The height from the lower surface of the second core body 16B to the second surface 29 increases toward the rear. The through holes 24 as the first locking portions 25 are provided in the front end portions of the first core body 16A and the second core body 16B, respectively.

[0067] In order to extract the hole forming formwork 1 from the concrete molded body 2, the worker first extracts the first core 16A from the concrete molded body 2, and then extracts the second core 16B from the concrete molded body 2. This allows the worker to peel off the two second outer peripheral surfaces 27 individually from the inner peripheral surfaces of the corresponding holes 3, so that the force required to extract the first core 16A and the second core 16B from the concrete molded body 2 is reduced. In addition, the worker can slide the first core 16A along the second surface 29 to extract the first core 16A from the concrete molded body 2 in a state in which the second outer peripheral surface 27 of the first core 16A is peeled off from the inner peripheral surface of the corresponding hole 3. After extracting the first core 16A and the second core 16B from the concrete molded body 2, the worker sequentially extracts each of the two divided frames 17 from the concrete molded body 2 by the same procedure as in the first embodiment. As a result, the hole forming formwork 1 is extracted from the concrete molded body 2.

[0068] Third embodiment Next, a third embodiment of the present invention will be described with reference to Fig. 7. Elements that are the same as or similar to those in the second embodiment are given the same reference numerals, and duplicated descriptions will be omitted. In the hole forming form 1 of this embodiment, the configuration of the core body 16 is different from that of the second embodiment.

[0069] The first core body 16A has a first protruding piece 30 protruding from the lower surface of the first core body 16A toward the second core body 16B, i.e., downward. In this embodiment, the first protruding piece 30 is provided in the center of the first core body 16A in the front-rear direction. The second core body 16B has a second protruding piece 31 protruding from the upper surface of the second core body 16B toward the first core body 16A, i.e., upward. The second protruding piece 31 is provided in the center of the front-rear direction of the second core body 16B so as to face the first protruding piece 30. The lower surface of the first protruding piece 30 (hereinafter referred to as the first surface 28) and the upper surface of the second protruding piece 31 (hereinafter referred to as the second surface 29) are in contact with each other. The first surface 28 and the second surface 29 are formed smoothly along the front-rear direction, and are inclined with respect to the two second outer circumferential surfaces 27 in a side view.

[0070] A gap is formed between the front portion of the first core body 16A and the front portion of the second core body 16B. Also, a gap is formed between the rear portion of the first core body 16A and the rear portion of the second core body 16B. This reduces the weight of each core body 16.

[0071] The hole forming form 1 has a spacer 32 for maintaining the vertical width dimension L1 of the core body 16 in cooperation with each of the protruding pieces 30, 31. The spacer 32 is arranged at the front end of each of the core bodies 16A, 16B and at the rear end of each of the core bodies 16A, 16B. The spacer 32 has a main part 32A arranged between the first core body 16A and the second core body 16B, and an end part 32B extending outwardly in the front and rear directions from the main part 32A. The vertical width dimension of the main part 32A is approximately equal to the vertical width dimension of the first protruding piece 30 and the second protruding piece 31 that are in contact with each other at positions facing each other. The vertical width dimension of the end part 32B may be equal to the vertical width dimension L1 of the core body 16.

[0072] To remove the hole forming formwork 1 from the concrete molded body 2, the worker first removes the spacer 32 closest to the worker from between the two cores 16A and 16B. After that, the worker removes the first core 16A from the concrete molded body 2, and then removes the second core 16B from the concrete molded body 2. Since each of the cores 16A and 16B is lightweight, the force required to remove each of the cores 16A and 16B is small. After that, the worker sequentially removes each of the two split frames 17 from the concrete molded body 2 using the same procedure as in the second embodiment. In this way, the hole forming formwork 1 is removed from the concrete molded body 2.

[0073] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to Figures 8 to 10. Elements that are the same as or similar to those in the first embodiment are given the same reference numerals, and duplicated explanations will be omitted. In the hole forming form 1 of this embodiment, the configuration of the core body 16 is different from that of the first embodiment, but the other configurations (the configuration of the divided frame body 17) are the same as those of the first embodiment.

[0074] 8, the core body 16 has a hollow support part 33 extending along the front-rear direction, two main body parts 34 held by the support part 33 so as to be movable in the up-down direction, and an expansion part disposed between the two main body parts 34 and expandable at least in the up-down direction. In this embodiment, the expansion part is a rubber expansion tube 35 that expands when a fluid is injected.

[0075] As also shown in FIG. 9, the support portion 33 is formed in a substantially rectangular parallelepiped shape. The support portion 33 is provided with two openings, a first opening 38 and a second opening 39, which communicate between the hollow space and the outside. The two first openings 38 are provided on the upper and lower surfaces of the support portion 33, respectively. The first opening 38 has a rectangular shape in a plan view. The width dimensions in the front-rear direction and the left-right direction of the first opening 38 are smaller than the width dimensions in the front-rear direction and the left-right direction of the corresponding upper and lower surfaces. The second opening 39 is provided on the front surface of the support portion 33.

[0076] Each of the two main bodies 34 is formed into a substantially rectangular parallelepiped that is long in the front-rear direction. The two main bodies 34 are disposed spaced apart from each other vertically, and are supported by the support portion 33 while passing through the corresponding first openings 38. The upper surface of the upper main body 34 and the lower surface of the lower main body 34 each form a corresponding second outer circumferential surface 27.

[0077] The lower part of the upper main body part 34 and the upper part of the lower main body part 34 are provided with overhanging parts 41 that overhang to the left and right. The overhanging parts 41 are plate-shaped with their surfaces facing up and down. The width dimensions in the front-rear direction and the left-right direction of the overhanging parts 41 are larger than the width dimensions in the front-rear direction and the left-right direction of the main body part 34. The width dimensions in the front-rear direction and the left-right direction of the overhanging parts 41 are also larger than the width dimensions in the front-rear direction and the left-right direction of the opening. The lower surface of the upper main body part 34 is joined to a part of the upper surface of the corresponding overhanging part 41. The upper surface of the lower main body part 34 is joined to a part of the lower surface of the corresponding overhanging part 41. In another embodiment, the main body part 34 and the overhanging parts 41 may be formed integrally.

[0078] A rubber plate 42 with its surface facing up and down is provided on the overhanging portion 41. The rubber plate 42 is joined to the upper and lower surfaces of the overhanging portion 41 that are not joined to the main body portion 34.

[0079] As shown in Fig. 8, the inflation tube 35 extends in the front-rear direction. The inflation tube 35 passes through the second opening 39 and is disposed in the hollow of the support part 33. A coupler 43 is attached to the front end of the inflation tube 35 for injecting fluid into the inflation tube 35 or discharging fluid from the inflation tube 35. The coupler 43 may be disposed in front of the second opening 39, or may be connected to a portion of the support part 33 that defines the second opening 39.

[0080] As shown in FIG. 9, the expansion tube 35 is expanded by injecting a fluid. As a result, the two main body parts 34 move in a direction away from each other, that is, vertically outward. When the main body part 34 moves vertically outward to a predetermined position, the rubber plate 42 provided on the protruding part 41 abuts against the back surface of the upper surface of the corresponding support part 33 and the back surface of the lower surface of the support part 33. This prevents the main body part 34 from slipping out of the support part 33. When the rubber plate 42 abuts against the corresponding back surface, the vertical width dimension L3 between the two second outer peripheral surfaces 27 is set to be equal to or larger than the vertical width dimension L2 from the upper end to the lower end of the split frame 17. As shown in FIG. 10, the expansion of the expansion tube 35 is released by discharging the fluid inside the expansion tube 35. As a result, the two main body parts 34 can move in a direction approaching each other, that is, vertically inward, so that the vertical width dimension L3 between the two second outer peripheral surfaces 27 becomes smaller than the vertical width dimension L2 from the upper end to the lower end of the split frame 17.

[0081] When the hole forming formwork 1 is placed at a predetermined position within the formwork for forming the concrete molded body 2, the worker should clamp each of the divided frame bodies 17 between the core body 16 with the expansion tube 35 inflated.

[0082] In order to remove the hole forming formwork 1 from the concrete molded body 2, the worker first releases the expansion of the expansion pipe 35 by discharging the fluid inside the expansion pipe 35. Next, the worker moves each main body 34 inwardly up and down. This causes the second outer peripheral surface 27 to peel off from the corresponding inner peripheral surface of the hole 3. After that, the worker removes the core body 16 from the concrete molded body 2, and then sequentially removes each of the two divided frames 17 from the concrete molded body 2 in the same manner as in the first embodiment. In this way, the hole forming formwork 1 is removed from the concrete molded body 2.

[0083] Fifth embodiment Next, a fifth embodiment of the present invention will be described with reference to Figures 11 to 13. Elements that are the same as or similar to those in the first embodiment are given the same reference numerals, and duplicated descriptions will be omitted.

[0084] The hole forming form 1 has a core body 16, two divided frames 17, and two holding bodies 45. The core body 16 is cylindrical and extends in the front-rear direction. The outer peripheral surface of the core body 16 is formed smoothly along the front-rear direction.

[0085] Each of the two retaining bodies 45 is formed from a solid member extending in the front-rear direction. The retaining bodies 45 are arranged spaced apart from each other so as to sandwich the core body 16 in the up-down direction. The surface facing the inner side in the up-down direction of each retaining body 45 is arc-shaped in a front cross-sectional view (FIG. 13) and is formed smoothly along the front-rear direction. The surface facing the inner side in the up-down direction of each retaining body 45 abuts against a part of the outer circumferential surface of the core body 16. In this way, each retaining body 45 sandwiches the core body 16 in the up-down direction.

[0086] The surfaces of each retainer 45 facing outward in the vertical direction form corresponding second outer peripheral surfaces 27 that cooperate with the first outer peripheral surfaces 20 provided on the split frame 17 to form the inner peripheral surface of the hole 3. The second outer peripheral surfaces 27 are surfaces that extend in the front-rear and left-right directions and are formed smoothly along the front-rear directions. In addition, the left and right side surfaces of each retainer 45 that are joined to the surfaces facing inward in the vertical direction of each retainer 45 and the second outer peripheral surfaces 27 of each retainer 45 are also formed smoothly along the front-rear directions.

[0087] 13, the left-right width of the face of each retainer 45 that abuts against a part of the outer circumferential surface of the core body 16 is wider than the left-right width of the second outer circumferential surface 27 of each retainer 45. That is, the retainer 45 is formed in a tapered shape that becomes wider from the second outer circumferential surface 27 toward the core body 16 in a front cross-sectional view. In this embodiment, the left-right width of the face of each retainer 45 that abuts against a part of the outer circumferential surface of the core body 16 is smaller than the diameter of the core body 16.

[0088] Each of the two split frames 17 is formed from a solid member. The split frames 17 are arranged spaced apart from each other so as to sandwich the core body 16 and each holding body 45 in the left-right direction. That is, each split frame 17 abuts against the corresponding left and right side surfaces of the holding body 45 and has an inner peripheral surface that abuts against the outer circumferential surface of the core body 16 in cooperation with the upper and lower inward facing surfaces of each holding body 45. The inner peripheral surface of each split frame 17 is formed smoothly along the front-rear direction.

[0089] Since the contact surfaces of the core body 16, the divided frames 17, and the holding bodies 45 are all smooth, the core body 16 can move back and forth relative to the divided frames 17 and the holding bodies 45. The holding bodies 45 can also move back and forth relative to the core body 16 and the divided frames 17.

[0090] In the operation of extracting the hole forming form 1 from the concrete molded body 2, an operator first moves the core body 16 forward, so that the core body 16 is extracted from the concrete molded body 2. As a result, a space is formed inside the hole forming form 1.

[0091] Next, the worker slides one of the retainers 45 vertically inward toward the space formed inside the hole forming form 1. This causes the second outer peripheral surface 27 of the retainer 45 to peel off from the inner peripheral surface of the corresponding hole 3. Since the retainers 45 are formed in a tapered shape that becomes wider from the second outer peripheral surface 27 toward the core body 16 side in a front cross-sectional view, it becomes easy to move each of the retainers 45 vertically inward toward the space formed inside the hole forming form 1 (see FIG. 13). Then, the worker moves one of the retainers 45 forward, so that the retainer 45 is extracted from the concrete molded body 2. Then, the worker further extracts the other retainer 45 from the concrete molded body 2 in the same procedure as that for extracting one of the retainers 45 from the concrete molded body 2.

[0092] In other embodiments, the worker may remove each retaining body 45 from the concrete molded body 2 by moving each retaining body 45 forward from its original position where it was clamping the core body 16, rather than sliding each retaining body 45 upward and downward inward.

[0093] As each retainer 45 is extracted from the concrete molded body 2, the space inside the hole forming form 1 expands. This allows each divided frame 17 to slide left and right. When the worker moves one divided frame 17 left and right inward toward the space formed inside the hole forming form 1, the first outer peripheral surface 20 of one divided frame 17 peels off from the inner peripheral surface of the corresponding hole 3. Then, the worker moves one divided frame 17 forward, so that the divided frame 17 is extracted from the concrete molded body 2. Then, the worker further extracts the other divided frame 17 from the concrete molded body 2 in the same procedure as the extraction of one divided frame 17 from the concrete molded body 2. As a result, the hole forming form 1 is extracted from the concrete molded body 2.

[0094] 11 to 13, by moving each divided frame 17 toward the space formed inside the hole forming form 1, the protrusions 23 (protrusions 22) on each divided frame 17 are released from the unevenness on the concrete molded body 2. In other words, each divided frame 17 can be moved in the direction to be removed from the concrete molded body 2.

[0095] Sixth embodiment Next, a sixth embodiment of the present invention will be described with reference to Fig. 14. Elements that are the same as or similar to those in the fifth embodiment are given the same reference numerals, and duplicated descriptions will be omitted.

[0096] The core body 16 has a rectangular shape in a front cross section extending in the front-rear direction. The top and bottom surfaces and the left and right side surfaces of the core body 16 are formed smooth along the front-rear direction.

[0097] The surfaces of each retainer 45 facing inwardly upward and downward are surfaces that abut against the corresponding upper and lower surfaces of the core body 16, and are approximately equal in size to the corresponding upper and lower surfaces of the core body 16. The inner peripheral surfaces of each divided frame 17 abut against the corresponding left and right side surfaces of each retainer 45 and the corresponding left and right side surfaces of the core body 16.

[0098] The hole forming form 1 further has a tubular member 46 and a recess 47 for receiving an end of the tubular member 46. The tubular member 46 may be, for example, a flexible resin pipe or a steel pipe.

[0099] The recess 47 is provided so as to be recessed downward from the second outer circumferential surface 27 of the upper holding body 45. The recess 47 may be a bottomed hole, or may be a through hole that vertically penetrates the upper holding body 45. The recess 47 may also be provided in the split frame 17.

[0100] When the lower end of the tubular member 46 is received in the recess 47, the upper end of the tubular member 46 may be located above the formwork for forming the concrete molded body 2 or the concrete pouring surface. In the operation of removing the hole forming formwork 1 from the concrete molded body 2, the worker first moves the tubular member 46 upward, whereby the tubular member 46 is removed from the concrete molded body 2. Thereafter, the worker sequentially moves the core body 16, each of the retaining bodies 45, and each of the divided frames 17, whereby the hole forming formwork 1 is removed from the concrete molded body 2.

[0101] As a result, in addition to the holes 3 formed by the hole forming formwork 1, the concrete molded body 2 is provided with passages (not shown) formed by the tubular members 46 from the top surface of the concrete molded body 2 to the holes 3. The passages serve as injection and discharge holes 13 for filling the holes 3 formed in the concrete molded body 2 with a filler such as non-shrink grout.

[0102] In another embodiment, the surfaces of each retainer 45 facing inward in the vertical direction may be smaller than the corresponding upper and lower surfaces of the core body 16. As a result, the upper and lower surfaces of the core body 16 that do not abut the surfaces facing inward in the vertical direction of each retainer 45 form the step surface 26. The inner peripheral surface of each divided frame body 17 may be provided so as to abut the step surface 26 in addition to the left and right side surfaces of each retainer 45 and the left and right side surfaces of the core body 16. As a result, when each divided frame body 17 clamps the core body 16 and each retainer 45, excessive movement of each divided frame body 17 in the vertical direction is suppressed by the step surface 26. Therefore, after the hole forming formwork 1 is placed at a predetermined position in the formwork for forming the concrete molded body 2, the divided frame body 17 is suppressed from moving in the vertical direction.

[0103] Seventh embodiment Next, a seventh embodiment of the present invention will be described with reference to Fig. 15. Elements that are the same as or similar to those in the fifth embodiment are given the same reference numerals, and duplicated descriptions will be omitted.

[0104] The core body 16 is a pipe material with a rectangular cross section, and four corners 49 abut against the corresponding divided frame body 17 and holding body 45. The divided frame body 17 and holding body 45 with which the corners 49 abut are provided with grooves 50 extending in the front-rear direction. The grooves 50 provided in the divided frame body 17 are recessed from the left and right inner faces of the divided frame body 17 toward the left and right outward. The grooves 50 provided in the holding body 45 are recessed from the top and bottom inner faces of the holding body 45 toward the top and bottom outward. In this embodiment, the grooves 50 are arc-shaped. The corners 49 are received in the grooves 50 in a state of abutting against the portions that define both edges of the grooves 50 and the portions that define the bottom of the grooves 50.

[0105] The hole forming form 1 may be removed from the concrete molded body 2 in the same manner as in the fifth embodiment. The core body 16 is lightweight because it is made of a tubular material. In addition, the corners 49 of the core body 16 abut against the corresponding divided frames 17 and holder 45, so the core body 16 can be easily removed from the concrete molded body 2. Furthermore, the corners 49 are received in the grooves 50, so rattling of the core body 16 relative to the divided frames 17 and holder 45 is suppressed.

[0106] Eighth embodiment Next, an eighth embodiment of the present invention will be described with reference to Fig. 16. Note that elements that are the same as or similar to those in the fifth embodiment are given the same reference numerals, and duplicated descriptions will be omitted.

[0107] The hole forming form 1 has a core body 16, two divided frame bodies 17, and one holding body 45. In a front cross-sectional view, the faces of the upper circumferential ends of the divided frame bodies 17 are located left and right inward of the faces of the lower circumferential ends. In other words, when the divided frame bodies 17 clamp the core body 16, the faces of the upper circumferential ends of the divided frame bodies 17 abut against each other, while the faces of the lower circumferential ends of the divided frame bodies 17 are spaced apart from each other.

[0108] The retaining body 45 is disposed below the core body 16 and is clamped between the split frame bodies 17 so that the left and right side surfaces of the retaining body 45 abut against the surfaces of the lower circumferential end portions of the corresponding split frame bodies 17.

[0109] The second outer peripheral surface 27 of the retainer 45 is provided with a plurality of ridges 23 for forming irregularities on the inner peripheral surface of the hole 3 in cooperation with the first outer peripheral surface 20. In other words, the plurality of ridges 23 are provided over the entire outer peripheral surface of the hole forming form 1.

[0110] In the operation of extracting the hole forming form 1 from the concrete molded body 2, an operator first moves the core body 16 forward, so that the core body 16 is extracted from the concrete molded body 2. As a result, a space is formed inside the hole forming form 1.

[0111] Next, the worker slides the retainer 45 upward toward the space formed inside the hole formation form 1. As a result, the second outer peripheral surface 27 of the retainer 45 peels off from the corresponding inner peripheral surface of the hole 3, and the tips of the multiple protrusions 23 move inward to the left and right from the tips of the convex parts formed on the inner peripheral surface of the hole 3. After that, the worker further moves the retainer 45 forward, and the retainer 45 is extracted from the concrete molded body 2. As a result, the space inside the hole formation form 1 expands.

[0112] Thereafter, the worker slides one of the divided frames 17 so as to rotate it in the circumferential direction toward the space formed inside the hole formation form 1, and then moves one of the divided frames 17 forward, thereby extracting one of the divided frames 17 from the concrete molded body 2. After that, the worker further extracts the other divided frame 17 from the concrete molded body 2 in the same procedure as that for extracting one of the divided frames 17 from the concrete molded body 2. In this way, the hole formation form 1 is extracted from the concrete molded body 2.

[0113] Although the description of the specific embodiment is finished above, the present invention is not limited to the above embodiment and modified examples, and can be widely modified and implemented. For example, in the above embodiment, the hole forming formwork 1 according to the present invention is used to form holes 3A and 3B provided in the column member 6 and the beam member 8, but it may be used to form a hole 3 provided in a wall member. In addition, reinforcing bars, reinforcing bars, tension members, anchors, and other members other than the reinforcing bars 12 may be inserted into the hole 3. In addition, the hole forming formwork 1 is used so that unevenness is formed on the left and right sides of the inner peripheral surface of the hole 3, but it may be used so that unevenness is formed on the upper and lower sides of the inner peripheral surface of the hole 3. In the third embodiment, the pouring and discharging holes 13 for filling a filler such as non-shrink grout are provided from the upper surface of the concrete molded body 2 to the hole 3, but the pouring and discharging holes 13 may be provided from the lower surface of the concrete molded body 2 to the hole 3. In addition, the specific configuration, arrangement, quantity, material, or extraction procedure of each member of each member may be appropriately changed within the scope of the present invention. Furthermore, all of the components shown in the above embodiment are not necessarily required, and may be selected as appropriate. [Explanation of symbols]

[0114] 1: Hole forming formwork 2: Concrete molding 3: Hole 16: Core body 16A: 1st core 16B:Second core 17: Split frame 20: First outer peripheral surface 22: Convex 25: First locking part 26: Step surface 27: Second outer peripheral surface 28: 1st page 29:Second side 30: First protrusion 31: Second protrusion 33: Support part 34: Main body 35: Expansion tube (expansion part) 45: Holding body 46: Tubular member 47: Recess 49: Corner L1: Width dimension in the vertical direction of the core body (dimension in the second direction of the two second outer surfaces) L2: Vertical width dimension of the split frame (dimension of the first outer surface in the second direction) L3: The vertical width dimension of the two second outer peripheral surfaces (the dimension of the two second outer peripheral surfaces in the second direction)

Claims

1. A hole forming form for forming a hole having an axially-oriented unevenness in at least a portion of a circumferential direction in a concrete molded body, A core body extending along the axial direction; a plurality of divided frame bodies extending along the axial direction and spaced apart from each other in a predetermined first direction perpendicular to the axial direction so as to sandwich the core body; Each of the plurality of divided frames has a first outer circumferential surface that forms a first portion of an inner circumferential surface of the hole, the first portion including the projections and recesses, and a plurality of protrusions that protrude outward from the first outer circumferential surface and form the projections and recesses, The core body is a hole forming form that is movable in the axial direction relative to the split frame bodies.

2. and two second outer circumferential surfaces, which cooperate with the first outer circumferential surface to form the inner circumferential surface of the hole and are smooth along the axial direction; The hole forming form according to claim 1 , wherein each of the two second outer peripheral surfaces forms a surface of the core body that faces each other in a second direction that intersects with the first direction.

3. The two second outer circumferential surfaces are parallel to each other in a side view, The core body includes a first core body and a second core body extending along the axial direction and including the corresponding second outer circumferential surface, a first surface of the first core body that forms a back surface of the second outer peripheral surface of the first core body and a second surface of the second core body that forms a back surface of the second outer peripheral surface of the second core body abut against each other; The hole forming form according to claim 2 , wherein the first surface and the second surface are formed smoothly along the axial direction.

4. The two second outer circumferential surfaces are parallel to each other in a side view, The core body includes a first core body and a second core body extending along the axial direction and including the corresponding second outer circumferential surface, The first core body has at least one first protruding piece protruding from a back side of the second outer circumferential surface toward the second core body, The second core body has at least one second protruding piece that protrudes from the back side of the second outer circumferential surface toward the first core body and abuts against the first protruding piece, The hole forming form as described in claim 2, wherein a first surface of the first protrusion that abuts against the second protrusion, and a second surface of the second protrusion that abuts against the first surface are each formed smoothly along the axial direction.

5. 5. The hole forming form according to claim 3, wherein the first surface and the second surface are inclined with respect to the two second outer peripheral surfaces in a side view.

6. The hole forming form as described in claim 2, wherein the core body has a hollow support portion extending along the axial direction, two main body portions held by the support portion so as to be movable in the second direction and including corresponding second outer circumferential surfaces, and an expansion portion disposed between the two main body portions and expandable at least in the second direction.

7. two second outer peripheral surfaces cooperating with the first outer peripheral surface to define the inner peripheral surface of the hole; two holders extending along the axial direction and including corresponding second outer circumferential surfaces; The hole forming form as described in claim 1, wherein each of the two holding bodies is arranged spaced apart in a second direction intersecting the first direction so as to sandwich the core body, and is movable in the second direction relative to the split frame body.

8. 8. The hole forming form according to claim 7, wherein the holding body is formed in a tapered shape whose width increases from the second outer circumferential surface toward the core body.

9. The split frame includes two split frames, The core body is a tube having a rectangular cross section, 8. The hole forming form according to claim 7, wherein four corners of the split frame and the supporting body are in contact with each other.

10. The hole forming form according to claim 7 , wherein the second outer circumferential surface is formed smoothly along the axial direction.

11. The hole forming form according to claim 2 or claim 7, wherein the core body has a plurality of step surfaces extending in the axial direction and the second direction in the portions of the core body that are clamped between the respective divided frame bodies.

12. The first outer circumferential surface has an arc shape in a cross section seen from the axial direction, The form for forming a hole according to claim 2 or claim 7, wherein, in the cross-sectional view, the dimension of the first outer peripheral surface in the second direction is set to be less than or equal to the dimensions of the two second outer peripheral surfaces in the second direction.

13. The hole forming form according to claim 12, wherein the plurality of convex portions form ridges extending in the circumferential direction, and in a portion near the circumferential end of the first outer peripheral surface, the radial dimension of the ridges becomes smaller the closer they are to the circumferential end.

14. 8. The hole forming form according to claim 2 or claim 7, wherein a first locking portion for locking a jig for pulling out the core body in the axial direction is provided on at least one end of the core body in the axial direction.

15. 8. A form for forming a hole as described in claim 2 or claim 7, comprising a tubular member forming a passage for a filler material from the outer surface of the concrete molded body to the hole, and a recess for receiving an end of the tubular member.

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