Hole forming mold and hole forming method for forming holes in concrete molded body

Abstract

To provide a hole molding die which enables formation of a hole that linearly extends and has unevenness on its inner peripheral surface, can be removed from a concrete molding after formation of the hole, and is comparatively inexpensively available, and a hole molding method using the hole molding die.SOLUTION: A hole molding die 1 includes a steel rod member 2 which extends in a predetermined direction and has a circular arc part 5 and a groove part 6 provided on its outer peripheral surface, and a slide member 3 which is fittable to the groove part 6, and is slidable in a predetermined direction to the steel rod member 2 in a state of being fit to the groove part 6. The outer peripheral surface of the circular arc part 5 includes a plurality of projections 7 which are provided in a circumferential direction or are inclined in the circumferential direction, and extend in parallel with each other. After the slide member 3 has been removed, when the steel rod member 2 is rotated in the circumferential direction, the circular arc part is stored in a gap formed by removing the slide member 3, the steel rod member 2 can be moved out from a hole 11 by slide movement.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a hole forming mold used when forming a concrete molded body to form holes in the concrete molded body, and to a hole forming method using the hole forming mold. [Background technology]

[0002] In some cases, concrete molded bodies are formed by pouring fluid concrete into a formwork, and holes for inserting reinforcing bars or the like are required. After the reinforcing bars or the like are inserted into the holes, grout is poured into them. It is necessary to provide irregularities on the inner circumferential surface of the holes so that shear forces in the extension direction of the reinforcing bars can be transmitted between the hardened grout and the concrete molded body.

[0003] If a steel pipe with an uneven surface is used as a mold, it is possible to create unevenness on the inner surface of the hole, but the steel pipe cannot be pulled out after the concrete has hardened, and the steel pipe becomes a dead-end formwork. Dead-end formwork leaves foreign matter in the concrete and increases costs, so it is sometimes desirable to avoid its use. Therefore, a hole-forming mold that can be used in such cases has been proposed.

[0004] For example, Patent Document 1 describes a through-hole forming mold equipped with a rubber expansion tube for forming a through-hole having an uneven inner peripheral surface. The through-hole forming mold is placed in a formwork with the rubber expansion tube in an expanded state, and is removed with the rubber expansion tube in a deflated state after concrete is poured and hardened. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-184235 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the through-hole molding die described in Patent Document 1 further includes a rigid cylindrical body including multiple arc-shaped segments and a flexible outer tube to prevent the rubber expansion body from deforming due to buoyancy and distorting the hole from a straight line. The processing of the rigid cylindrical body is complicated, and the number of components is large, resulting in increased manufacturing costs. Furthermore, the outer tube, which comes into contact with the concrete, deteriorates rapidly, so repeated use of the through-hole molding die requires replacing the outer tube, which also contributes to increased costs.

[0007] In view of the above background, an object of the present invention is to provide a hole forming mold that can form a hole that extends linearly and has an uneven inner surface, that can be removed from a concrete molded body after the hole is formed, and that can be used at a relatively low cost, and a hole forming method using this hole forming mold. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, one aspect of the present invention is a hole forming mold (1) used when forming a concrete molded body (10) for forming a hole (11) in the concrete molded body, the molded body comprising: a steel bar member (2) extending in a predetermined direction, the steel bar member having an outer peripheral surface that is arc-shaped with respect to a predetermined center in a cross-sectional view, one or more arc portions (5) extending in the predetermined direction, and one or more groove portions (6) that are recessed from an extended arc line of the outer peripheral surface of the arc portions in the cross-sectional view and extend in the predetermined direction; and slide members (3) that are the same number as the groove portions and can be fitted in the corresponding groove portions and can slide in at least one of the predetermined directions relative to the steel bar member while fitted in the groove portions, wherein the outer peripheral surface of the arc portions is circumferentially the arc portions and the groove portions are alternately arranged along the circumferential direction, and when the steel bar member is rotated in the circumferential direction by a predetermined angle, the side surfaces of the arc portions are positioned more inward in the circumferential direction than the side surfaces of the grooves before rotation, and the sliding member has an outer peripheral surface that coincides with the extended arc line or is positioned radially outward of the extended arc line when fitted into the grooves, and the outer peripheral surface of the sliding member is parallel to the predetermined direction or moves away from the steel bar member as it moves toward one of the predetermined directions when fitted into the grooves. Here, the "transverse section" means a cross section perpendicular to the predetermined direction.

[0009] According to this aspect, since the rod member has a protrusion, a partially uneven surface can be formed on the inner peripheral surface of the hole. Furthermore, by rotating the steel rod member in the circumferential direction so that the arc portion fits into the gap created after removing the slide member, the steel rod member with the protrusion can be easily removed from the concrete molded body by sliding it. Furthermore, since a highly rigid steel rod member is used, the hole is formed so that the central axis is straight. Furthermore, since the hole forming mold has a relatively simple configuration, the manufacturing cost of the hole forming mold can be reduced. Furthermore, since the steel rod member is highly durable and the slide member can be made of a highly durable material, it can be reused, and the cost of forming the hole can be reduced.

[0010] In the above aspect, it is preferable that the number of the arc portions (5) and the groove portions (6) is two, the boundaries between the arc portions and the groove portions extend in the radial direction in the cross-sectional view, the two arc portions have equal diameters and equal central angles (θ1), and the two groove portions have equal central angles (θ2). Here, the "central angle" of a groove portion means the angle formed by two line segments extending from the two boundaries between a groove portion and an adjacent arc portion to the center of the arc (center of the center) defined by the outer circumferential surface of the arc portion in the cross-sectional view.

[0011] According to this embodiment, only two slide members are required, and the shapes of the two slide members can be made common to both. Furthermore, when rotating the steel bar member in the circumferential direction, it can be rotated either clockwise or counterclockwise, improving workability. Furthermore, the contact area between the side surface of the slide member and the arc portion is reduced, reducing friction and facilitating the sliding movement of the slide member.

[0012] In the above aspect, the hole forming die (1) may preferably be circular in cross section when the slide members (3) are fitted into the corresponding grooves (6).

[0013] According to this aspect, when the slide member is slid, the contact area with the concrete molded body can be made small, and the frictional force is reduced, making it easier for the slide member to slide.

[0014] One aspect of the present invention is a method for forming the hole (11) in the concrete molded body (10) using the hole forming mold (1) of the above aspect, comprising the steps of installing a formwork (12) for forming the outer shape of the concrete molded body and the hole forming mold, pouring concrete (13) into the formwork, and removing the formwork and the hole forming mold, wherein the removing step includes the steps of sliding the slide member (3) in the predetermined direction to remove the slide member from the concrete molded body and the steel bar member (2), rotating the steel bar member in one of the circumferential directions to position the arc portion (5) in the gap created by removing the slide member, and moving the steel bar member in the predetermined direction to remove the steel bar member from the concrete molded body.

[0015] According to this aspect, holes that extend linearly and have irregularities on their inner peripheral surfaces can be formed in the concrete molded body easily and at low cost. [Effects of the Invention]

[0016] According to the above aspects, it is possible to provide a hole forming mold that can form a hole that extends linearly and has an uneven inner surface, can be removed from the concrete molded body after the hole is formed, and can be used at a relatively low cost, and a hole forming method using this hole forming mold. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an explanatory diagram showing a hole forming mold according to an embodiment and a method of using the mold (when pouring concrete); [Figure 2] 1 is an explanatory diagram showing a hole-forming mold according to an embodiment and a method of using the mold (first stage during demolding); FIG. [Figure 3]1 is an explanatory diagram showing a hole-forming mold according to an embodiment and a method of using the mold (second stage during demolding); FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, the hole-forming die 1 according to the embodiment of the present invention will be described with reference to the drawings. In Fig. 1 to Fig. 3, Fig. A is a cross-sectional view perpendicular to the extension direction of the hole-forming die 1 (a cross-sectional view taken along line AA in Fig. B), and Fig. B is a partial cross-sectional side view taken along line BB in Fig. A.

[0019] As shown in FIG. 1, the hole forming die 1 includes a steel bar member 2 extending in a predetermined direction, and two slide members 3 extending in the extension direction of the steel bar member 2 and used in combination with the steel bar member 2.

[0020] The steel bar member 2 includes a cylindrical central portion 4, two arc portions 5 that bulge radially relative to the central portion 4 and have an arc-shaped outer surface when viewed in cross section (a cross section perpendicular to the extension direction of the steel bar member 2), and extend in the extension direction of the steel bar member 2, and two groove portions 6 defined by providing the arc portions 5 relative to the central portion 4.

[0021] The outer peripheral surfaces of the two arc portions 5 form an arc relative to the center of the central portion 4 in a cross-sectional view. A plurality of ridges 7 extending along the circumferential direction are provided on the outer peripheral surface of the arc portion 5. It is preferable that the diameters (lengths from the center of the central portion 4 to the outer peripheral surfaces of the arc portions 5) of the two arc portions 5 are equal to each other and that the central angles θ1 are equal to each other. It is preferable that the side surfaces that define the circumferential ends of the arc portions 5 are perpendicular to the circumferential direction.

[0022] In a cross-sectional view, the grooves 6 are recessed from an extended arc line of the outer peripheral surface of the arc portion 5 including the ribs 7, and extend in the extension direction of the steel bar member 2. The bottom surfaces of the grooves 6 are defined by the outer peripheral surface of the center portion 4, and the side surfaces forming the circumferential ends of the grooves 6 are defined by the side surfaces that define the circumferential ends of the arc portion 5.

[0023] The arc portions 5 and the groove portions 6 are alternately arranged in the circumferential direction. The arc portions 5 and the groove portions 6 are configured such that, in a cross-sectional view, when the steel bar member 2 is rotated in the circumferential direction by a predetermined angle, the side surfaces of the arc portions 5 are positioned circumferentially inward relative to the side surfaces of the groove portions 6 before rotation. Therefore, when these side surfaces are arranged along the radial direction in a cross-sectional view, the central angle θ1 of each arc portion 5 is smaller than the central angle θ2 of the groove portions 6. Here, the central angle θ2 of the groove portions 6 is the angle formed by two line segments extending from the two boundaries between the groove portions 6 and the adjacent arc portions 5 to the center of the center portion 4 in a cross-sectional view. In the illustrated example, the central angle θ1 of the arc portions 5 is slightly smaller than 90°, and the central angle θ2 of the groove portions 6 is slightly larger than 90°.

[0024] The slide member 3 is fitted into the groove portion 6 so as to be slidable in the extension direction of the steel bar 2. In a cross-sectional view, the slide member 3 has an arc shape with a predetermined width in the radial direction. When the slide member 3 is fitted into the steel bar 2, the inner circumferential surface of the slide member 3 abuts the outer circumferential surface of the center portion 4, and the side surfaces forming the circumferential ends of the slide member 3 slidably abut the side surfaces forming the circumferential ends of the arc portion 5. When the slide member 3 is fitted into the steel bar 2, the outer circumferential surface of the slide member 3 is located on an arc line extending from the outer circumferential surface of the arc portion 5 in a cross-sectional view. Therefore, when the slide member 3 is fitted into the steel bar 2, the combined shape of the steel bar 2 and the slide member 3 forms a cylindrical shape. The slide member 3 is preferably made of steel, but any material having sufficient rigidity to withstand the poured concrete 13 may be used. For example, fiber-reinforced plastic such as carbon fiber, or plastic may also be used.

[0025] When the slide member 3 is fitted into the groove portion 6, the outer peripheral surface of the slide member 3 may be located radially outward of the extended arc line of the arc portion 5. The outer peripheral surface of the slide member 3 is parallel to the extension direction of the steel bar member 2, but instead, it may be inclined or curved so as to move away from the steel bar member 2 as it moves toward one side of the extension direction of the steel bar member 2.

[0026] The number of arc portions 5 and groove portions 6 may be one or more than two. The central angles θ1 of the arc portions 5 do not have to coincide with each other, and the central angles θ2 of the groove portions 6 do not have to coincide with each other. However, when the steel bar member 2 is rotated by a predetermined angle in one circumferential direction, the outer peripheral surfaces of all arc portions 5 must be located on or radially inward of the outer peripheral surface of the slide member 3 fitted into the groove portions 6 before rotation, and the side surfaces forming the circumferential ends of all arc portions 5 must be located on or circumferentially inward of the side surfaces forming the circumferential ends of the groove portions 6 before rotation. Therefore, the central angle θ1 of each arc portion 5 must be smaller than the central angle θ2 of the groove portion 6 adjacent to it in the rotational direction.

[0027] The multiple ridges 7 may extend parallel to one another at an angle in the circumferential direction, like threads, instead of extending along the circumferential direction. In this case, the angle of inclination of the ridges 7 relative to the circumferential direction is common not only to the ridges 7 provided on one arc portion 5 but also to the ridges 7 provided on different arc portions 5, so that the steel rods 2 can rotate in the circumferential direction around the ridges 7 relative to the hardened concrete 13.

[0028] Next, a method for forming holes 11 in a concrete molded body 10 using the hole forming mold 1 will be described with reference to Figures 1 to 3. The case where the holes 11 are through holes will be described as an example, but the holes 11 may also be bottomed holes.

[0029] As shown in Figure 1, workers assemble a formwork 12 for forming the outer shape of a concrete molded body 10, and place a hole forming mold 1 inside the formwork 12. The extension length of the steel rod members 2 and the slide members 3 is equal to the extension length of the hole 11 to be formed. Workers pour fluid concrete 13 into the formwork 12 so as to bury the hole forming mold 1.

[0030] When the poured concrete 13 has hardened to the extent that it can be removed from the formwork, the worker removes the formwork 12 and, as shown in Figure 2, slides the slide member 3 by pulling it out or pushing it out in its extension direction, thereby removing it from the steel rod member 2 and the concrete molded body 10.

[0031] As shown in Figure 3, the worker rotates the steel rod member 2 in the circumferential direction so that the arc portion 5 is accommodated in the gap created by removing the slide member 3, and then removes the steel rod member 2 from the concrete molded body 10 by pulling or pushing it out in the direction of its extension. In this way, a concrete molded body 10 having a hole 11 is formed.

[0032] The effects of the hole-forming die 1 according to the embodiment will be described.

[0033] Because the steel rod 2 has the ribs 7, it is possible to form a partially uneven surface 14 on the inner circumferential surface of the hole 11. Because the ribs 7 extend circumferentially, the steel rod 2 can be rotated circumferentially. By rotating the steel rod 2 circumferentially so that the arc portion 5 fits into the gap that is created after the slide member 3 is removed, the steel rod 2 with the ribs 7 can be easily removed from the concrete molded body 10 by sliding it.

[0034] Since a highly rigid steel rod member 2 is used, the hole 11 is formed so that the central axis is linear.

[0035] The hole forming mold 1 is made up of a relatively simple structure consisting of the steel rod members 2 and the slide members 3, which reduces the manufacturing costs of the hole forming mold 1. The steel rod members 2 are highly durable, and the slide members 3 can be made of a highly durable material. Therefore, even if the steel rod members 2 and slide members 3 that come into contact with the concrete 13 are washed, the molds do not collapse and they can be used repeatedly, reducing the cost of forming the hole 11.

[0036] Since there are two arc portions 5 and two groove portions 6, the number of slide members 3 is also two, which prevents an increase in the number of members. In addition, the central angles θ1 of the two arc portions 5 and the central angles θ2 of the two groove portions 6 are equal so that the steel bar member 2 is point-symmetric in cross section. This allows the shapes of the two slide members 3 to be equal to each other, and also allows the steel bar member 2 to be rotated either clockwise or counterclockwise when rotated circumferentially, improving workability.

[0037] With the slide member 3 fitted into the groove portion 6, the hole forming mold 1 has a circular shape in cross section, so when the slide member 3 is slid relative to the concrete molded body 10, the side surfaces forming the circumferential ends of the slide member 3 do not come into contact with the inner surface of the hole 11, suppressing an increase in frictional resistance and facilitating the sliding movement of the slide member 3. As the circumferential side surfaces of the arc portion 5 extend radially in cross section, the contact area between the side surfaces of the slide member 3 and the side surfaces of the arc portion 5 is reduced, reducing frictional force and facilitating the sliding movement of the slide member 3.

[0038] If the outer surface of the slide member 3 is inclined or curved so as to move away from the steel rod member 2 as it moves toward one side of the extension direction of the steel rod member 2, the friction force between the outer surface of the slide member 3 and the inner surface of the hole 11 is reduced when the slide member 3 is slid toward that side of the extension direction, making the sliding movement easier.

[0039] Although the specific embodiment has been described above, the present invention is not limited to the above embodiment and modifications, and can be implemented in a wide variety of ways. For example, the central portion does not have to be cylindrical, and the bottom surface of the groove may have a shape that defines a protrusion along the extension direction of the steel bar member. [Explanation of symbols]

[0040] 1: Hole mold 2: Steel bar member 3: Slide member 4: Center 5: Arc section 6: Groove 7:Protrusion 10: Concrete molding 11: Hole 12: Formwork 13: Concrete 14: Uneven surface θ1: Central angle of the arc θ2: Central angle of the groove

Claims

1. A hole forming mold used when forming a concrete molded body, for forming holes in the concrete molded body, A steel bar member extending in a predetermined direction, the steel bar member having an outer peripheral surface that is arc-shaped with respect to a predetermined center in a cross-sectional view, and including one or more arc portions extending in the predetermined direction, and one or more groove portions that are recessed in the cross-sectional view from an extended arc line of the outer peripheral surface of the arc portion and extend in the predetermined direction; slide members, the number of which is equal to the number of grooves, which can be fitted into the corresponding grooves and can slide in at least one of the predetermined directions relative to the steel bar member when fitted into the grooves; Equipped with the outer peripheral surface of the arc portion includes a plurality of ridges extending parallel to one another along a circumferential direction or inclined in the circumferential direction, The arc portions and the groove portions are alternately provided along the circumferential direction, and are configured such that, in the cross-sectional view, when the steel bar member is rotated in the circumferential direction by a predetermined angle, a side surface of the arc portion is positioned more inward in the circumferential direction than a side surface of the groove portion before rotation, the slide member has an outer circumferential surface that coincides with the extension arc line or is positioned radially outward of the extension arc line in the cross-sectional view when fitted to the groove portion, A hole forming die, wherein the outer peripheral surface of the slide member is parallel to the predetermined direction when the slide member is fitted in the groove portion, or moves away from the steel bar member as it moves toward one of the predetermined directions.

2. the number of the arc portions and the number of the groove portions are each two, In the cross-sectional view, a boundary between the arc portion and the groove portion extends in the radial direction, The two arcuate portions have equal diameters and equal central angles, The hole-forming die according to claim 1 , wherein the central angles of the two grooves are equal to each other.

3. The hole-forming die according to claim 1 or 2, wherein the cross section is circular when the slide members are fitted into the corresponding grooves.

4. A method for forming the hole in the concrete molded body using the hole forming mold according to any one of claims 1 to 3, a step of installing a formwork for forming the outer shape of the concrete molded body and the hole forming mold; pouring concrete into the formwork; removing the mold and the hole forming mold; Equipped with The removing step includes: Sliding the slide member in the predetermined direction to remove the slide member from the concrete molded body and the steel rod member; rotating the steel rod member in one of the circumferential directions and arranging the arc portion in a gap created by removing the slide member; moving the steel rod member in the predetermined direction to remove the steel rod member from the concrete molded body; A method comprising:

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