Cutting auxiliary device and cutting method

Abstract

A cutting auxiliary device and a cutting method are provided that can specifically achieve optimal processing of metal members when extending metal members embedded in existing concrete structures. [Solution] The cutting auxiliary device 20 has a support member 21 (first member 22, second member 30) attached to the existing PC steel fixing fixture 4, and a fitting member 39 fitted to this support member 21, and supports a rotating shaft 9 with a cutting blade 10 positioned on the outer periphery of the existing PC steel fixing fixture 4. When the first member 22 rotates, the rotating shaft 9 is guided by the second member 30, and the cutting blade 10 revolves along the outer surface of the existing PC steel fixing fixture 4, forming a cutting groove along the outer periphery of the existing PC steel fixing fixture 4.

Description

[Technical Field]

[0001] The present invention relates to a cutting auxiliary device used when processing the end of a metal component when extending the metal component embedded in a concrete structure, and a cutting method for processing the end of a metal component. [Background technology]

[0002] Conventionally, bridges and other structures are made up of main girders, cross girders, concrete deck slabs, etc. In PC bridges in particular, to reinforce each component such as the deck slab and cross girders, inserted or embedded prestressing steel strands are tensioned and then fixed with anchoring devices. When bridge girders need to be repaired or widened, new prestressing steel strands are connected to the existing prestressing steel strands and new concrete is poured, as described in Patent Document 1 below, for example (hereinafter, the technology described in Patent Document 1 will be referred to as the "Publicly Known Invention 1").

[0003] According to the invention in the publicly known document 1, the ends of the existing concrete members are chipped off, and the ends of the prestressing steel are cut to remove the anchoring devices. After installing new bearing plates, cones and anchoring nuts, and tensioning the prestressing steel with jacks, the new prestressing steel is connected to the existing prestressing steel via a coupler, and concrete is poured.

[0004] In the technology described in Patent Document 2 below (hereinafter, the technology described in Patent Document 2 will be referred to as the "Publicly Known Patent Document 2 Invention"), an anchoring sleeve attached to the end of an existing PC steel member is processed, and then a coupler is connected to this processed anchoring sleeve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-148870 [Patent Document 2] Patent No. 6830610 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the invention of the prior art document 1 requires many parts and many steps, making the work complicated. Also, the specific method for processing the sleeve in the prior art document 2 is not clear.

[0007] As described above, for bridge girders where widening was not anticipated, it is necessary to extend the prestressing steel members, but the optimal construction method has not yet been established.

[0008] The present invention has been proposed in consideration of the above-mentioned situation, and aims to provide a cutting auxiliary device and a cutting method that can specifically achieve optimal processing of metal components when extending metal components embedded in existing concrete structures. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the cutting auxiliary device of the present invention has a support member that supports the rotating shaft of the cutting blade while the cutting blade is positioned on the outer periphery of a metal member protruding from the end of an existing concrete structure, and is attached to the metal member, and the support member has a first member that rotates around the metal member as an axis, causing the cutting blade to rotate along the outer surface of the metal member, and a second member that guides the cutting blade as it rotates, and when the cutting blade is in contact with the outer surface of the metal member, as the first member rotates, the cutting blade rotates around the outer periphery of the metal member while being guided by the second member, thereby forming a cutting groove along the outer surface of the metal member.

[0010] The cutting assist device according to the present invention is characterized in that the first member has a support hole portion through which the rotating shaft portion is passed, the second member has a guide hole portion through which the rotating shaft portion is passed, the support hole portion is formed long and perpendicular to the rotating shaft portion toward the metal member, the support hole portion has a farthest support portion farthest from the metal member and a nearest support portion nearest to the metal member, the guide hole portion is formed in a shape that extends in the direction in which the cutting blade is rotated and gradually approaches the metal member, the guide hole portion has a farthest guide portion farthest from the metal member and a nearest guide portion nearest to the metal member, and when the support member is attached to the metal member, the farthest support portion and the farthest guide portion overlap, or the nearest support portion and the nearest guide portion overlap.

[0011] The cutting assist device according to the present invention is characterized in that the first member is formed in a concave shape that mates with the second member and has a first hole portion through which the metal member is passed, the second member is formed in a convex shape that mates with the first member and has a second hole portion through which the metal member is passed, and the first member and the second member are fitted together so as to be rotatable relative to each other with the metal member passed through.

[0012] The cutting assist device according to the present invention is characterized in that the outer surface of the first member and / or the outer surface of the second member has a rotational position identification means that indicates the degree to which the first member has rotated relative to the second member.

[0013] The cutting assist device according to the present invention is characterized in that the outer surface of the first member and the outer surface of the second member have the same polygonal shape.

[0014] The cutting assist device according to the present invention is characterized by having an engagement member that is engaged with the support member and restricts relative rotation between the first member and the second member.

[0015] The cutting auxiliary device of the present invention is characterized in that the fitting member has a plurality of restricting hole portions through which the rotating shaft portion is passed, and the distance from the restricting hole portion to the metal member is different for each restricting hole portion.

[0016] The cutting auxiliary device of the present invention is characterized in that the multiple restriction hole portions include a farthest restriction portion that is farthest from the metal member and a nearest restriction portion that is nearest to the metal member, and when the engagement member is engaged with the support member, the farthest restriction portion overlaps with the guide hole portion between the farthest guide portion and the nearest guide portion, or the nearest restriction portion overlaps with the nearest guide portion.

[0017] The cutting auxiliary device of the present invention is characterized in that the metal member is the end of a tension member embedded in the existing concrete structure, a tension member anchor, or the end of a reinforcing bar embedded in the existing concrete structure.

[0018] The cutting method of the present invention uses a cutting auxiliary device and includes: an attachment step of attaching the first member and the second member to a metal member protruding from the end of an existing concrete structure; a predetermined angle rotation step of rotating the cutting blade, with the rotating shaft portion passed through the support hole portion and the guide hole portion, while in contact with the outer surface of the metal member and rotating the first member by a predetermined rotation angle relative to the second member, thereby forming the cutting groove gradually deeper along the outer surface of the metal member; a full circumference rotation step of attaching the joint member to the first member and the second member and rotating them once, thereby forming the cutting groove around the entire circumference on the outer surface of the metal member; and a detachment step of removing the joint member, wherein the predetermined angle rotation step, the full circumference rotation step, and the detachment step are repeated in order until the cutting groove reaches the desired depth. [Effects of the Invention]

[0019] The cutting assist device of the present invention includes a support member attached to the metal member, which supports the rotating shaft of the cutting blade while the cutting blade is positioned on the outer periphery of the metal member protruding from the end of the existing concrete structure. The support member rotates around the metal member as an axis, and includes a first member that rotates the cutting blade along the outer surface of the metal member, and a second member that guides the cutting blade as it rotates. When the cutting blade contacts the outer surface of the metal member, as the first member rotates, the cutting blade is guided by the second member and rotates around the outer periphery of the metal member, forming a cutting groove along the outer surface of the metal member. The cutting blade is contacted with the outer surface of the metal member to cut the outer surface, and as the cutting blade rotates around the metal member in this state, a cutting groove along the outer periphery of the metal member is formed. Therefore, when extending the metal member via an extension member such as a coupler, an optimal cutting groove can be formed that fits the extension member.

[0020] In a cutting assist device according to the present invention, a first member has a support hole through which a rotating shaft is passed, and a second member has a guide hole through which the rotating shaft is passed, the support hole being formed long and perpendicular to the rotating shaft toward the metal member, the support hole having a farthest support portion farthest from the metal member and a nearest support portion closest to the metal member, the guide hole being formed so as to extend in the direction in which the cutting blade is rotated and gradually approach the metal member, the guide hole having a farthest guide portion farthest from the metal member and a nearest guide portion closest to the metal member, and when the support member is attached to the metal member, the farthest support portion and the farthest guide portion overlap, or the nearest support portion and the nearest guide portion overlap. By passing the rotating shaft through the support hole and the guide hole, the rotating shaft moves within the range of the support hole in a direction approaching the metal member and moves within the range of the guide hole in a direction outer circumferentially of the metal member. As a result, the cutting blade moves along the outer surface of the metal member and is pressed against the metal member, forming a cutting groove on the outer surface of the metal member that gradually deepens along the outer surface. When the rotating shaft is passed through the support hole and the guide hole, and the farthest support portion and the farthest guide portion overlap, the cutting blade is separated from (or in contact with) the metal member. When the first member rotates in this state, the rotating shaft is pressed by the support hole and guided by the guide hole, so it moves along the outer surface of the metal member and approaches the metal member. As a result, the cutting blade comes into contact with (or sinks into) the outer surface of the metal member and moves along the outer surface while being pressed against it. Therefore, the metal member can be cut gradually deeper.

[0021] In the cutting assist device according to the present invention, the first member is formed in a concave shape that mates with the second member and has a first hole through which a metal member is passed, and the second member is formed in a convex shape that mates with the first member and has a second hole through which the metal member is passed, so that the first member and the second member are fitted together to be relatively rotatable with the metal member passed through. This allows the first member to rotate stably. This makes it possible to form an optimal cutting groove for fitting an extension member or the like.

[0022] The cutting assist device according to the present invention has a rotation position identifying means for identifying the degree to which the outer surface of the first member and / or the outer surface of the second member has rotated relative to the second member. Based on the degree to which the first member has rotated, the extent to which the cutting blade has pivoted and the length of the cutting groove can be determined.

[0023] In the cutting assist device according to the present invention, the outer surfaces of the first member and the second member have the same polygonal shape. By aligning the vertices, it is easy to see the degree to which the first member has rotated.

[0024] The cutting assist device according to the present invention has a fitting member that fits to the support member and restricts the relative rotation of the first member and the second member. When the fitting member rotates while fitted to the support member (the first member and the second member), the first member and the second member rotate simultaneously. As the first member rotates, the metal member is cut gradually deeper. When the cutting groove reaches the desired depth, the fitting member fits to the support member and the first member and the second member rotate simultaneously, forming an annular cutting groove of the desired depth.

[0025] As the first member rotates, the rotating shaft moves along the outer surface of the metal member and approaches the metal member, so the distance between the rotating shaft and the outer surface of the metal member always varies in the circumferential direction of the metal member. Therefore, in the cutting assist device according to the present invention, the engagement member has a plurality of restricting holes through which the rotating shaft is passed, and the distance from the restricting hole to the metal member varies for each restricting hole. Depending on the position of the rotating shaft, one of the restricting holes can be selected, and the engagement member can be engaged with the support member (first member and second member) at that position.

[0026] In the cutting assist device according to the present invention, the multiple restriction holes include a farthest restriction portion farthest from the metal member and a nearest restriction portion closest to the metal member. When the engagement member is engaged with the support member, the farthest restriction portion overlaps with the guide hole between the farthest guide portion and the nearest guide portion, or the nearest restriction portion overlaps with the nearest guide portion. When the engagement member is engaged with the support member (first member and second member), if the rotating shaft portion is positioned between the farthest guide portion and the nearest guide portion, the rotating shaft portion is passed through the farthest restriction portion. If the rotating shaft portion is positioned in the nearest guide portion, the rotating shaft portion is passed through the nearest restriction portion. Therefore, the farthest restriction portion or the nearest restriction portion is selected depending on the position of the rotating shaft, and the engagement member can be engaged with the support member (first member and second member) at that position.

[0027] The cutting assist device according to the present invention is capable of extending various metal members embedded in concrete structures, such as the end of a tendon, a tendon anchor, or the end of a reinforcing bar embedded in an existing concrete structure.

[0028] The cutting method of the present invention includes a mounting step of attaching a first member and a second member to a metal member protruding from the edge of an existing concrete structure, a predetermined-angle rotation step of rotating a cutting blade with a rotating shaft passing through a support hole and a guide hole against the outer surface of the metal member and rotating the first member relative to the second member by a predetermined angle to gradually form a cutting groove along the outer surface of the metal member, a full-circle rotation step of attaching a mating member to the first member and the second member and rotating them once to form a cutting groove around the entire circumference of the outer surface of the metal member, and a detachment step of removing the mating member, and the predetermined-angle rotation step, full-circle rotation step, and detachment step are repeated in order until the cutting groove reaches the desired depth. Thus, when extending the metal member via an extension member or the like, it is possible to form an optimal annular cutting groove for the extension member to fit into. [Brief explanation of the drawings]

[0029] [Figure 1]FIG. 1 is a schematic cross-sectional side view of a cutting assist device according to an embodiment of the present invention in use. [Figure 2] FIG. 2 is an exploded perspective view of the cutting assist device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a rear view of a first member of the cutting assist device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a rear view of the second member of the cutting assist device according to the embodiment of the present invention. [Figure 5] FIG. 5 is a rear view of a fitting member of a cutting assist device according to an embodiment of the present invention. [Figure 6] FIG. 6 is a first explanatory view for explaining the operation of the cutting assist device according to the embodiment of the present invention. [Figure 7] FIG. 7 is a second explanatory view for explaining the operation of the cutting assist device according to the embodiment of the present invention. [Figure 8] FIG. 8 is a third explanatory view for explaining the operation of the cutting assist device according to the embodiment of the present invention. [Figure 9] FIG. 9 is a fourth explanatory view for explaining the operation of the cutting assist device according to the embodiment of the present invention. [Figure 10] FIG. 10 is a fifth explanatory view for explaining the operation of the cutting assist device according to the embodiment of the present invention. [Figure 11] FIG. 11 is a sixth explanatory view for explaining the operation of the cutting assist device according to the embodiment of the present invention. [Figure 12] FIG. 12 is a seventh operation explanatory view for explaining the operation of the cutting assist device according to the embodiment of the present invention. [Figure 13] FIG. 13 is a first explanatory diagram showing the procedure of the cutting method using the cutting assist device according to the embodiment of the present invention. [Figure 14] FIG. 14 is a second explanatory diagram showing the procedure of the cutting method using the cutting assist device according to the embodiment of the present invention. [Figure 15] FIG. 15 is a third explanatory diagram showing the procedure of the cutting method using the cutting assist device according to the embodiment of the present invention. [Figure 16] FIG. 16 is a fourth explanatory diagram showing the procedure of the cutting method using the cutting assist device according to the embodiment of the present invention. [Figure 17] FIG. 17 is a schematic side view illustrating the procedure of the cutting method according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The cutting assist device 20 and cutting method according to an embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows a cross section of the cutting assist device 20 according to this embodiment in use. In the following description, it is assumed that the ground guard and balustrade (neither of which are shown) have been removed in advance from the end of the existing concrete structure.

[0031] As shown in Figure 1, existing prestressing tendons 3, which are longitudinal metal members acting as tendons, are embedded in a concrete deck 1 (hereinafter referred to as the existing concrete deck 1), which is an existing concrete structure constituting a bridge girder. The ends of the existing prestressing tendons 3 protrude from an end face 2 of the existing concrete deck 1. The ends of the existing prestressing tendons 3 are fastened to the end face 2 by an existing prestressing tendon anchor 4 and an existing anchor plate 6, which are metal members. The existing anchor plate 6 is embedded in the end face 2. A cutting auxiliary device 20 is attached to the existing prestressing tendon anchor 4 together with a cutting tool 7, and cuts the outer periphery of the existing prestressing tendon anchor 4. The cutting tool 7 is comprised of a power tool 8 with a rotating shaft 9 attached to it, and a cutting blade 10 attached to the tip of the rotating shaft 9. The diameter of the cutting blade 10 is larger than the diameter of the rotating shaft 9.

[0032] The cutting auxiliary device 20 has a support member 21 attached to the existing PC steel anchoring tool 4, and a fitting member 39 fitted to the support member 21. The support member 21 and fitting member 39 have the rotating shaft portion 9 of the cutting blade 10 passing through them, and support the rotating shaft portion 9 with the cutting blade 10 positioned on the outer periphery of the existing PC steel anchoring tool 4. The support member 21 is made up of a first member 22 and a second member 30.

[0033] Here, the first member 22, the second member 30, and the mating member 39 will be explained based on the drawings. Figure 2 shows the cutting assist device 20 disassembled into the individual members 22 and 30. In the following explanation, the direction toward the existing concrete slab 1 will be referred to as the front, and the direction away from the existing concrete slab 1 will be referred to as the back (see Figures 1 and 2).

[0034] As shown in FIG. 2 , the first member 22 is formed in a regular dodecagonal cylindrical shape. Specifically, the first member 22 has a first member front end surface 23 having a flat surface of a regular dodecagon and a first member side surface 24 extending rearward from the periphery of the first member front end surface 23. The outer surface of the first member side surface 24 is formed in a regular dodecagon. The inner surface of the first member side surface 24 is formed in an annular shape. The rear portion of the first member 22 is formed in a concave shape by the first member front end surface 23 and the first member side surface 24. A circular first hole 25 is formed in the center of the first member front end surface 23, and one support hole 26 is formed around the first hole 25. The first hole 25 and the support hole 26 penetrate the first member front end surface 23 in the front-rear direction. An existing prestressing steel member anchor 4 is passed through the first hole 25, and a rotation shaft 9 is passed through the support hole 26. The shape of the first hole portion 25 is formed following the shape of the outer surface of the existing PC steel member anchoring device 4. The shape of the support hole portion 26 is formed to be larger than the rotation shaft portion 9.

[0035] The second member 30 has a second-member front portion 31, which is its front portion, and a second-member rear portion 32, which is its rear portion. Specifically, the second-member front portion 31 is formed in a cylindrical shape, and the second-member rear portion 32 is formed in a regular dodecagonal tubular shape. The diameter of the second-member front portion 31 is shorter than the diameter of the second-member rear portion 32. Therefore, a step is formed at the boundary between the second-member front portion 31 and the second-member rear portion 32, and the second member 30 is formed in a convex shape by the second-member front portion 31 and the second-member rear portion 32. The convex shape of the second member 30 is formed to match the concave shape of the first member 22. A circular second hole portion 33 is formed in the center of the second member 30, and one guide hole portion 34 is formed around this second hole portion 33. The second hole portion 33 and the guide hole portion 34 penetrate the second-member front portion 31 and the second-member rear portion 32 in the front-rear direction. The existing PC steel member fixing device 4 is passed through the second hole portion 33, and the rotating shaft portion 9 is passed through the guide hole portion 34. The shape of the second hole portion 33 is formed to match the shape of the outer surface of the existing PC steel member fixing device 4. The guide hole portion 34 is formed larger than the rotating shaft portion 9, and is curved in an arc along the second hole portion 33.

[0036] The mating member 39 is formed in a regular dodecagonal cylindrical shape. Specifically, the mating member 39 has a mating member rear end surface 40 having a flat surface of a regular dodecagon and a mating member side surface 41 extending forward from the periphery of the mating member rear end surface 40. The outer and inner surfaces of the mating member side surface 41 are formed in a regular dodecagon. The front portion of the mating member 39 is formed in a concave shape by the mating member side surface 41 and the mating member rear end surface 40. The concave shape of the mating member 39 is formed to match the outer surface of the first member side surface 24 and the outer surface of the second member rear portion 32. A circular mating hole 42 is formed in the center of the mating member rear end surface 40, and three restriction holes 43 are formed around the mating hole 42. The mating hole portion 42 and the restriction hole portion 43 penetrate the rear end surface portion 40 of the mating member in the front-to-rear direction. The existing PC steel member fixing device 4 is passed through the mating hole portion 42, and the rotating shaft portion 9 is passed through the restriction hole portion 43. The shape of the mating hole portion 42 is formed to match the shape of the outer surface of the existing PC steel member fixing device 4. The shape of the restriction hole portion 43 is formed to match the shape of the outer surface of the rotating shaft portion 9.

[0037] Next, the shapes and arrangements of the support hole 26 of the first member 22, the guide hole 34 of the second member 30, and the restriction hole 43 of the joint member 39 will be described with reference to the drawings. Figures 3 to 5 show the members 22, 30, and 39 as viewed from behind. Figure 3 shows the support hole 26 of the first member 22, Figure 4 shows the guide hole 34 of the second member 30, and Figure 5 shows the restriction hole 43 of the joint member 39. When the existing PC steel member anchoring device 4 is passed through the first hole 25 of the first member 22, the second hole 33 of the second member 30, and the joint hole 42 of the joint member 39, the members 22, 30, and 39 are aligned on the same axis, and the axis common to all the members is defined as the central axis A.

[0038] As shown in FIG. 3, the support hole 26 is an elongated hole formed perpendicular to the front-rear direction toward the first hole 25. In the figure, the width of the support hole 26 is a size that follows the diameter of the rotating shaft 9, and the vertical width is longer than the diameter of the rotating shaft 9. Therefore, the support hole 26 is large enough for the rotating shaft 9 to pass through, and the rotating shaft 9 can move in the support hole 26 in a direction toward or away from the first hole 25, but cannot move in the circumferential direction of the first hole 25. The support hole 26 is formed by connecting the central axis A and one vertex T of a regular dodecagon. 22-1 A line L passing through 22-1 The part of the support hole 26 that is farthest from the circumference of the first hole 25 is the farthest support part 27. The part of the support hole 26 that is closest to the circumference of the first hole 25 is the nearest support part 29. The part of the support hole 26 that is between the farthest support part 27 and the nearest support part 29 is the middle support part 28. The distance D from the circumference of the first hole 25 to the middle support part 28 22-2 is the distance D from the circumference of the first hole portion 25 to the farthest support portion 27 22-3 and the distance D from the circumference of the first hole portion 25 to the nearest support portion 29 is shorter than 22-1 Therefore, each distance is longer than the distance D 22-3 , distance D 22-2 , distance D 22-1 (distance D 22-3 >Distance D 22-2 >Distance D 22-1 The farthest support 27, the middle support 28 and the nearest support 29 are connected to the vertex T22-1 and the line L 22-1 They are all aligned above.

[0039] As shown in FIG. 4 , the guide hole 34 extends along the second hole 33 in the circumferential direction of the second hole 33. The vertical width of the support hole 26 in the same figure is sized to match the diameter of the rotating shaft 9, and the horizontal width is longer than the diameter of the rotating shaft 9. Therefore, the guide hole 34 is sized to allow the rotating shaft 9 to pass through, and the rotating shaft 9 can move in the circumferential direction of the second hole 33 within the guide hole 34, but cannot move linearly toward or away from the second hole 33. The guide hole 34 is formed in a shape that gradually approaches the second hole 33 as it extends in the circumferential direction of the second hole 33. Therefore, the distance from the circumference of the second hole 33 varies depending on the portion of the guide hole 34.

[0040] The right end of the guide hole 34 in the figure is the farthest guide portion 35, which is the portion farthest from the circumference of the second hole 33. The farthest guide portion 35 is located between the central axis A and one vertex T of the regular dodecagon. 30-1 A line L passing through 30-1 The left end of the guide hole 34 in the figure is the nearest guide portion 38, which is the portion closest to the circumference of the second hole 33. The nearest guide portion 38 is located between the central axis A and one vertex T of the regular dodecagon. 30-4 A line L passing through 30-4 The guide hole 34 has an intermediate guide portion between the farthest guide portion 35 and the nearest guide portion 38. The intermediate guide portion has a first intermediate guide portion 36 and a second intermediate guide portion 37. The first intermediate guide portion 36 is located between the central axis A and one vertex T of the regular dodecagon. 30-2 A line L passing through 30-2 The second intermediate guide portion 37 is located on the center axis A and one vertex T of the regular dodecagon. 30-3 A line L passing through 30-3 The distance D from the circumference of the second hole portion 33 to the first intermediate guide portion 36 is 30-3 and the distance D from the circumference of the second hole portion 33 to the second intermediate guide portion 37 30-2is the distance D from the circumference of the second hole portion 33 to the farthest guide portion 35 30-4 and the distance D from the circumference of the second hole portion 33 to the nearest guide portion 38 is 30-1 The distance D from the circumference of the second hole portion 33 to the first intermediate guide portion 36 is longer than 30-3 is the distance D from the circumference of the second hole portion 33 to the second intermediate guide portion 37 30-2 Therefore, each distance is longer than the distance D 30-4 , distance D 30-3 , distance D 30-2 , distance D 30-1 (distance D 30-4 >Distance D 30-3 >Distance D 30-2 >Distance D 30-1 ). straight line L 30-1 , L 30-2 , L 30-3 and L 30-4 are offset by 30 degrees. Therefore, the line L 30-1 and the line L 30-2 The angle between is 30 degrees and the line L 30-1 and the line L 30-3 The angle between is 60 degrees and the line L 30-1 and the line L 30-4 The angle between is 90 degrees.

[0041] As shown in Figure 5, the three restriction holes 43 are arranged at equal intervals on a circumference centered on the mating hole 42. The size of the restriction holes 43 corresponds to the diameter of the rotating shaft 9. Therefore, the restriction holes 43 are large enough for the rotating shaft 9 to pass through, and the rotating shaft 9 cannot move within the restriction holes 43. The distance from the circumference of the mating hole 42 to each of the restriction holes 43 is different for each restriction hole 43.

[0042] Of the restriction holes 43, the upper restriction hole 43 in the figure is the farthest restriction part 44, and is the farthest from the circumference of the fitting hole 42. The farthest restriction part 44 is located between the central axis A and one vertex T of the regular dodecagon. 39-1 A line L passing through 39-1Among the restriction holes 43, the lower restriction hole 43 in the figure is the nearest restriction portion 46, which is the closest to the circumference of the fitting hole 42. The nearest restriction portion 46 is located between the central axis A and one vertex T of the regular dodecagon. 39-3 A line L passing through 39-3 Of the restriction holes 43, the one on the left side in the figure is the middle restriction portion 45. The distance D from the circumference of the fitting hole 42 to the middle restriction portion 45 is 39-2 is the distance D from the circumference of the fitting hole 42 to the farthest restriction portion 44 39-3 and the distance D from the circumference of the fitting hole 42 to the nearest restriction portion 46 is shorter than 39-1 Therefore, each distance is longer than the distance D 39-3 , distance D 39-2 , distance D 39-1 (distance D 39-3 >Distance D 39-2 >Distance D 39-1 The farthest restriction portion 44, the intermediate restriction portion 45, and the nearest restriction portion 46 are each offset by 90 degrees. 39-1 and the line L 39-2 The angle between is 90 degrees and the line L 39-1 and the line L 39-3 The angle between them is 180 degrees.

[0043] The first member 22, second member 30, and mating member 39 configured as described above are mated as follows. That is, as shown in FIGS. 2 to 5, the convex shape of the first member 22 and the concave shape of the second member 30 are mated. Because the inner surface of the first member side portion 24 is annular and the second member front portion 31 is cylindrical, the first member 22 and the second member 30 can rotate relative to each other about the central axis A when mated. The outer surfaces of the second member rear portion 32 and the first member side portion 24 are both regular dodecagons and have the same shape, so the outer surfaces are aligned. Because the inner surface of the mating member side portion 41 is formed as a regular dodecagon, the first member 22 and the second member 30 are mated with the concave shape of the mating member 39. When the mating member 39 is mated, relative rotation between the first member 22 and the second member 30 is restricted. The first hole 25 of the first member 22, the second hole 33 of the second member 30, and the mating hole 42 of the mating member 39 are all the same shape and aligned coaxially, so the existing PC steel member fixing device 4 can be inserted into each of the holes 25, 33, and 42. Furthermore, the support hole 26 of the first member 22, the guide hole 34 of the second member 30, and the regulating hole 43 of the mating member 39 are aligned coaxially depending on the posture of each of the members 22, 30, and 39, so the rotating shaft 9 can be inserted into each of the holes 26, 34, and 43.

[0044] Next, the arrangement of the holes 26, 34, 43 when the first member 22, the second member 30, and the mating member 39 are mated will be described with reference to the drawings, as well as the relationship between the holes 26, 34, 43 as the members 22, 30, 39 rotate. Figures 6 to 12 show the mated members 22, 30, 39 as viewed from the rear, and show how the positions of the holes 26, 34, 43 of the members 22, 30, 39 change as the members 22, 30, 39 rotate.

[0045] As shown in FIG. 6, the apex T 22-1 and the vertex T of the second member 30 30-1In this state, the farthest support portion 27 of the support hole portion 26 and the farthest guide portion 35 of the guide hole portion 34 overlap (hereinafter referred to as the "initial state"). Therefore, the rotating shaft portion 9 arranged at the farthest support portion 27 and the farthest guide portion 35 is at the farthest position from the existing PC steel member fixing device 4. In the initial state, the cutting blade 10 is not in contact with the existing PC steel member fixing device 4 or is in slight contact therewith.

[0046] The first member 22 rotates counterclockwise relative to the second member 30, and the vertex T 22-1 The vertex T of the second member 30 30-1 to the vertex T on the left 30-2 When the first member 22 is displaced to the position shown in FIG. 7 , the first member 22 is rotated 30 degrees from the initial position relative to the second member 30. In this position, the intermediate support portion 28 of the support hole 26 and the first intermediate guide portion 36 of the guide hole 34 overlap (hereinafter referred to as the "first cutting state"). As the first member 22 rotates, the rotating shaft 9 moves from the farthest support portion 27 to the intermediate support portion 28 in the support hole 26 and simultaneously moves from the farthest guide portion 35 to the first intermediate guide portion 36 in the guide hole 34. Therefore, the rotating shaft 9 moves toward the existing prestressing tendon fixing device 4 while revolving around the outer periphery of the existing prestressing tendon fixing device 4. From the initial position to the first cutting state, the cutting blade 10 contacts the existing prestressing tendon fixing device 4 and gradually cuts the existing prestressing tendon fixing device 4 as it rotates. A cutting groove G is formed on the outer surface of the existing prestressing tendon fixing device 4.

[0047] As shown in FIG. 8 , the engagement member 39 engages with the first member 22 and the second member 30 in the first cutting state. In this state, the farthest restriction portion 44 of the restriction hole 43 overlaps with the intermediate support portion 28 of the support hole 26 and the first intermediate guide portion 36 of the guide hole 34 (hereinafter referred to as the “first cutting maintenance state”). In the first cutting maintenance state, the rotating shaft portion 9 is immobile in each hole 28, 36, and 44. Therefore, when the engagement member 39 rotates together with the first member 22 and the second member 30, the rotating shaft portion 9 rotates 360 degrees around the existing prestressing steel member fixing device 4 while maintaining its distance from the existing prestressing steel member fixing device 4. The cutting blade 10 cuts the outer surface of the existing prestressing steel member fixing device 4 around the entire circumference. The cutting groove G formed on the outer surface of the existing prestressing steel member fixing device 4 is annular.

[0048] When the fitting member 39 is removed from the first member 22 and the second member 30, the first member 22 and the second member 30 are again allowed to rotate relative to each other. 22-1 The vertex T of the second member 30 30-2 to the vertex T on the left 30-3 9, the first member 22 is rotated 30 degrees relative to the second member 30 from the first cutting state. In this state, the intermediate support portion 28 of the support hole 26 and the second intermediate guide portion 37 of the guide hole 34 overlap (hereinafter referred to as the "second cutting state"). In the second cutting state, as the first member 22 rotates, the rotating shaft 9 moves within the intermediate support portion 28 of the support hole 26 and simultaneously moves from the first intermediate guide portion 36 to the second intermediate guide portion 37 of the guide hole 34. Therefore, the rotating shaft 9 moves closer to the existing prestressing tendon fixing device 4 and revolves around the outer periphery of the existing prestressing tendon fixing device 4. From the first cutting state to the second cutting state, the cutting blade 10 cuts deeper into the existing prestressing tendon fixing device 4 as it revolves.

[0049] As shown in FIG. 10 , the engagement member 39 engages with the first member 22 and the second member 30 in the second cutting state. In this state, the intermediate restricting portion 45 of the restricting hole 43 overlaps with the intermediate support portion 28 of the support hole 26 and the second intermediate guide portion 37 of the guide hole 34 (hereinafter referred to as the “second cutting maintenance state”). In the second cutting maintenance state, the rotating shaft 9 is immobile at each of the holes 28, 37, and 45. Therefore, when the engagement member 39 rotates together with the first member 22 and the second member 30, the rotating shaft 9 rotates 360 degrees around the existing prestressing steel member fixing device 4 while maintaining a distance from the existing prestressing steel member fixing device 4. When the engagement member 39 rotates once in the second cutting maintenance state, the cutting blade 10 cuts the outer surface of the existing prestressing steel member fixing device 4 around the entire circumference to the depth of the cutting groove G formed in the second cutting state.

[0050] When the fitting member 39 is removed from the first member 22 and the second member 30, the first member 22 and the second member 30 are again allowed to rotate relative to each other. 22-1 The vertex T of the second member 30 30-3 to the vertex T on the left 30-4 11 , the first member 22 is rotated 30 degrees relative to the second member 30 from the second cutting state. In this state, the nearest support portion 29 of the support hole 26 and the nearest guide portion 38 of the guide hole 34 overlap (hereinafter referred to as the "third cutting state"). In the third cutting state, as the first member 22 rotates, the rotating shaft 9 moves from the intermediate support portion 28 to the nearest support portion 29 in the support hole 26 and simultaneously moves from the second intermediate guide portion 37 to the nearest guide portion 38 in the guide hole 34. Therefore, the rotating shaft 9 moves closer to the existing prestressing tendon anchor 4 and revolves around the outer periphery of the existing prestressing tendon anchor 4. As the cutting state changes from the second cutting state to the third cutting state, the cutting blade 10 cuts deeper into the existing prestressing tendon anchor 4 as it rotates.

[0051] As shown in FIG. 12 , the engagement member 39 engages with the first and second members 22 and 30 in the third cutting state. In this state, the proximal restricting portion 46 of the restricting hole 43 overlaps with the proximal support portion 29 of the support hole 26 and the proximal guide portion 38 of the guide hole 34 (hereinafter referred to as the “third cutting maintenance state”). In the third cutting maintenance state, the rotating shaft 9 is immobile at each of the holes 29, 38, and 46. Therefore, when the engagement member 39 rotates together with the first and second members 22 and 30, the rotating shaft 9 rotates 360 degrees around the existing prestressing steel member anchor 4 while maintaining its distance from the existing prestressing steel member anchor 4. When the engagement member 39 rotates once in the third cutting maintenance state, the cutting blade 10 cuts the outer surface of the existing prestressing steel member anchor 4 around the entire circumference to the depth of the cutting groove G formed in the third cutting state.

[0052] As shown in FIGS. 6 to 12, the apex T 22-1 , each vertex T of the second member 30 30-1 ~T 30-4 and each vertex T of the joint member 39 39-1 ~T 39-3 Since each vertex T 22-1 ,T 30-1 ~T 30-4 ,T 39-1 ~T 39-3 function as a rotation position identifying means for indicating the degree of rotation of each of the members 22, 30, and 39. That is, when the first member 22 is rotated 30 degrees relative to the second member 30, the vertex T 22-1 The vertex T of the second member 30 30-1 to the vertex T on the left 30-2 In addition, when rotating the joint member 39 once, the joint member 39 is moved to a specific vertex T 39-1 After checking the position of the specific vertex T 39-1 Simply rotate the fitting member 39 until it returns to the same position.

[0053] Next, the steps of the cutting method using the cutting assist device 20 will be described with reference to the drawings. Figures 13 to 16 show the steps of the cutting method. The cutting method includes at least an attachment step, a predetermined angle rotation step, a full rotation step, and a removal step.

[0054] In the installation procedure, as shown in FIG. 13 , the first member 22 and the second member 30 are attached to the existing PC steel anchor 4 protruding from the end surface 2 of the existing concrete deck 1. Specifically, the convex shape of the first member 22 and the concave shape of the second member 30 are mated. The first hole 25 of the first member 22 and the second hole 33 of the second member 30 are aligned coaxially, and the farthest support portion 27 of the support hole 26 of the first member 22 and the farthest guide portion 35 of the guide hole 34 of the second member 33 are aligned coaxially (see FIG. 6 , initial state). The rotating shaft 9 is passed through the farthest support portion 27 and the farthest guide portion 35. Because a cutting blade 10 is attached to the tip of the rotating shaft 9, the rear end of the rotating shaft 9 is passed through the support hole 26 from the front end surface 23 of the first member. In this state, the first member 22 and the second member 30 are attached to the existing PC steel member fixing device 4 as the support member 21.

[0055] As shown in FIG. 14 , the existing prestressing tendon anchor 4 is inserted into the first hole 25 of the first member 22 and the second hole 33 of the second member 30, and the cutting blade 10 is placed against the outer surface of the existing prestressing tendon anchor 4. At this time, a contact bar 19 is sandwiched between the existing concrete slab 1 and the first member 22 as a spacing member. The contact bar 19 maintains a constant distance between the end face 2 of the existing concrete slab 1 and the front end face 23 of the first member, preventing the support member 21 from getting too close to the existing concrete slab 1 and causing the cutting blade 10 to be pinched between the end face 2 and the front end face 23 of the first member. A power tool 8 is attached to the rear end of the rotating shaft 9.

[0056] In the predetermined angle rotation procedure, the first member 22 is rotated 30 degrees relative to the second member 30 while the cutting blade 10 is in contact with the outer surface of the base portion 5 of the existing prestressing steel member fixing device 4. Specifically, with the power tool 8 operating and the cutting blade 10 rotating, the second member 30 is fixed with a pipe wrench or the like, and the first member 22 is rotated around the existing prestressing steel member fixing device 4 as an axis. The cutting blade 10 revolves along the outer surface of the base portion 5 while being guided by the second member 30. The cutting blade 10 is pressed against the outer surface of the base portion 5, cutting the outer surface. Furthermore, as the first member 22 rotates, the cutting blade 10 forms a gradually deeper cutting groove G along the outer surface of the base portion 5 (see FIG. 7 , first cutting state).

[0057] In the full rotation procedure, as shown in Fig. 15, the power tool 8 is removed from the rotating shaft 9, and the engagement member 39 is attached to the first member 22 and the second member 33. At this time, the rotating shaft 9 is passed through the farthest restricting portion 44 of the restricting hole 43 of the engagement member 39 (see Fig. 8, first cutting maintenance state). Furthermore, in the full rotation procedure, as shown in Fig. 16, the power tool 8 is again attached to the rear end of the rotating shaft 9, and with the engagement member 39 engaged with the first member 22 and the second member 30, the existing PC steel member anchor 4 is rotated once around the axis, thereby forming a cutting groove G around the outer surface of the base portion 5.

[0058] In the removal procedure, the power tool 8 is removed from the rotating shaft 9, and the fitting member 39 is removed from the first member 22 and the second member 30. The power tool 8 is attached to the rotating shaft 9, and the procedure returns to the predetermined angle rotation procedure.

[0059] In FIG. 14 , in the second predetermined-angle rotation procedure, the first member 22 is rotated 30 degrees relative to the second member 30. As the first member 22 rotates, the cutting blade 10 gradually deepens and forms a cutting groove G along the outer surface of the base portion 5 (see FIG. 9 , the second cutting state). In FIG. 15 , in the second full-circle rotation procedure, when the fitting member 39 is attached to the first member 22 and the second member 30, the rotating shaft 9 is passed through the intermediate restricting portion 45 of the restricting hole 43 of the fitting member 39 (see FIG. 10 , the second cutting state). Furthermore, in FIG. 16 , with the fitting member 39 fitted to the first member 22 and the second member 30, the fitting member 39 is rotated once around the existing prestressing steel member anchor 4 as an axis, thereby forming a cutting groove G around the entire circumference of the outer surface of the base portion 5. After the removal procedure, the procedure returns to the predetermined-angle rotation procedure.

[0060] In FIG. 14 , in the third rotation step, the first member 22 is rotated 30 degrees relative to the second member 30. As the first member 22 rotates, the cutting blade 10 gradually deepens the cutting groove G along the outer surface of the base portion 5 (see FIG. 11 , the third cutting state). In FIG. 15 , in the third full-circle rotation step, when the fitting member 39 is attached to the first member 22 and the second member 30, the rotating shaft 9 is passed through the nearest restricting portion 46 of the restricting hole 43 of the fitting member 39 (see FIG. 12 , the third cutting state). Furthermore, in FIG. 16 , with the fitting member 39 engaged with the first member 22 and the second member 30, the fitting member 39 is rotated once around the existing prestressing steel member anchor 4 as an axis, thereby forming the cutting groove G around the entire circumference of the outer surface of the base portion 5. Finally, the removal step is performed.

[0061] As described above, the predetermined angle rotation procedure, the full circumference rotation procedure, and the removal procedure are repeated in order until the depth of the cut groove G reaches the desired depth.

[0062] Next, a cutting method according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 17 shows an outline of the steps of the cutting method according to the second embodiment. The cutting method according to the second embodiment involves an exposure step in which the ends of reinforcing bars 18, which are metal members, are exposed from the ends of substructure 17 of a bridge girder, which is an existing concrete structure. The installation step, predetermined angle rotation step, full rotation step, and removal step are as described above, so duplicated explanations will be omitted below.

[0063] As shown in Figure 17, in a state where large diameter reinforcing bars 18 are embedded in the concrete of a substructure 17, in the exposure procedure, the concrete is chipped with a water jet or the like (not shown) to expose the reinforcing bars 18. A cutting assist device 20 is attached to the reinforcing bars 18, and cutting grooves are formed in the reinforcing bars 18.

[0064] Next, the effects of the above-described embodiment will be described.

[0065] As described above, the cutting assist device 20 includes the first and second members 22 and 30 attached to the existing prestressing tendon anchor 4 and the engagement member 39 that engages with the first and second members 22 and 30. The rotating shaft 9 of the cutting blade 10 passes through the first and second members 22 and 30, supporting the rotating shaft 9 with the cutting blade 10 positioned on the outer periphery of the existing prestressing tendon anchor 4 (see FIG. 16 ). As the first member 22 rotates around the existing prestressing tendon anchor 4, the rotating shaft 9 is guided by the second member 30, and the cutting blade 10 pivots along the outer surface of the base 5 of the existing prestressing tendon anchor 4, forming a cutting groove G along the outer periphery of the existing prestressing tendon anchor 4. Therefore, when extending the existing prestressing tendon anchor 4 via the coupler 12, an optimal cutting groove G can be formed that engages with the coupler 12.

[0066] The support hole portion 26 of the first member 22 is formed perpendicular to the rotation axis portion 9 and extends toward the existing PC steel fixing device 4, and has a farthest support portion 27 furthest from the existing PC steel fixing device 4, a nearest support portion 29 closest to the existing PC steel fixing device 4, and an intermediate support portion 28 located between the farthest support portion 27 and the nearest support portion 29 (see Figure 3).On the other hand, the guide hole portion 34 of the second member 30 extends in the direction in which the cutting blade 10 is rotated and is formed in a shape that gradually approaches the existing PC steel fixing device 4, and has a farthest guide portion 35 furthest from the existing PC steel fixing device 4, a nearest guide portion 38 closest to the existing PC steel fixing device 4, and a first intermediate guide portion 36 and a second intermediate guide portion 37 located between the farthest guide portion 35 and the nearest guide portion 38 (see Figure 4). In the initial state, the rotating shaft 9 arranged in the farthest support part 27 and the farthest guide part 35 is located at the farthest position from the existing PC steel member fixing tool 4 (see Figure 6), and as the cutting state changes from the first cutting state to the second cutting state to the third cutting state, the cutting blade 10 is gradually pressed against the outer surface of the existing PC steel member fixing tool 4, forming cutting grooves G in the existing PC steel member fixing tool 4 (see Figures 7 to 12). Therefore, the outer peripheral surface of the base part 5 can be excavated gradually deeper.

[0067] In particular, since the first member 22 is formed in a concave ring shape and the second member 30 is formed in a convex cylindrical shape, when the convex shape of the first member 22 and the concave shape of the second member 30 are engaged with each other, the first member 22 and the second member 30 can rotate relatively about the central axis A (see FIG. 2). Therefore, the first member 22 rotates stably.

[0068] Since the outer surface of the first member 22 is formed into a regular dodecagon and the outer surface of the second member rear part 32 of the second member 30 is formed into the same regular dodecagon as the first member 22, it functions as a rotation position identification means that indicates the degree to which the first member 22 has rotated relative to the second member 30 (see FIG. 2). Therefore, based on the degree to which the first member 22 has rotated, the degree to which the cutting blade 10 has turned and the length of the cutting groove G can be determined. Since the vertices of the regular dodecagon are offset by 30 degrees, each vertex T 22-1 ,T 30-1 ~T 30-4 ,T 39-1 ~T39-3 If each one shifts, you can see that it has rotated 30 degrees.

[0069] The engaging member 39 engages with the first member 22 and the second member 30, so when it rotates in this state, the first member 22 and the second member 30 rotate simultaneously. As the first member 22 rotates, the existing PC steel member fixing device 4 is cut gradually deeper, and when the depth of the cut groove G reaches the desired depth, the engaging member 39 engages with the first member 22 and the second member 30, and the first member 22 and the second member 30 rotate simultaneously, forming a circular cut groove G with the desired depth.

[0070] The joint member 39 has a farthest restricting portion 44 farthest from the existing PC steel member anchoring device 4, a nearest restricting portion 46 nearest to the existing PC steel member anchoring device 4, and a distance D from the existing PC steel member anchoring device 4 to the farthest restricting portion 44. 39-3 and the distance D from the existing PC steel anchor 4 to the nearest restricting portion 46 39-1 and an intermediate restricting portion 45 that is longer than the first member 22 (see FIG. 5). As the first member 22 rotates, the rotating shaft portion 9 moves along the outer surface of the existing PC steel member fixing device 4 and approaches the existing PC steel member fixing device 4. Therefore, the distance between the rotating shaft portion 9 and the outer surface of the existing PC steel member fixing device 4 is always different in the outer circumferential direction of the existing PC steel member fixing device 4. However, by selecting the farthest restricting portion 44, the intermediate restricting portion 45, or the nearest restricting portion 46 depending on the position of the rotating shaft portion 9, the mating member 39 can be mated to the first member 22 and the second member 30 at that position.

[0071] It should be noted that the angles in the present invention include approximate values ​​as well as the exact values ​​(for example, 30 degrees, 90 degrees, etc.) described above as the embodiments. In another embodiment of the present invention, the first member is rotated clockwise relative to the second member. In this case, the guide hole of the second member has a right end as the nearest guide portion and a left end as the farthest guide portion when viewed from the rear. Also, the right restriction hole of the mating member has a middle restriction portion when viewed from the rear. In another embodiment, the outer surface of the first member is circular or polygonal. Polygonal shapes include an equilateral triangle, a regular decagon, or a regular decagon with a larger number of vertices. The number of vertices of a polygon is related to the predetermined rotation angle in the predetermined angle rotation procedure, so the predetermined rotation angle is calculated by dividing 360 degrees by the number of vertices. In another alternative embodiment, the rotational position identifying means is a scale. In another alternative embodiment, only the first member has a rotational position identifying means and the second member does not have a rotational position identifying means. In another alternative embodiment, only the second member has a rotational position identifying means and the first member does not have a rotational position identifying means. Another alternative embodiment does not have a rotational position identification means. In other embodiments, the number of restriction holes in the fitting member is arbitrary, such as one, two, or four or more. Another alternative embodiment does not have a mating member. In another embodiment, a cutting groove is cut at a desired position in the existing PC steel anchor. In another alternative embodiment, the cutting grooves are cut into the existing tendons.

[0072] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made to the present invention without departing from the scope of the claims. [Explanation of symbols]

[0073] 1 Existing concrete floor slab (concrete structure) 2 End face 3 Existing PC steel (tension members, metal components) 4. Existing PC steel anchors (metal parts) 5. Base 6 Pre-set mounting plate 7 Cutting tools 8 Power tools 9 Rotating shaft 10 cutting blade 17 Substructure 18 Reinforced concrete 19. Stick 20 Cutting aids 21 Support member 22 First member 23 First member front end surface 24 First member side part 25 First hole 26 Support hole 27 Farthest support part 28 Intermediate support 29 Nearest support part 30 Second member 31 Second member front part 32 Rear part of second member 33 Second hole 34 Guide hole 35 Farthest guide part 36 First intermediate guide part 37 Second intermediate guide section 38 Recent Guide Department 39 Joints 40 Rear end surface of mating member 41 Side portion of fitting member 42 Engagement hole 43 Restriction hole 44 Farthest regulation part 45 Intermediate Regulation Department 46 Recent Regulation Department A center axis G cutting groove T vertex L straight line D distance

Claims

1. The cutting blade is disposed on the outer periphery of a metal member protruding from the end of the existing concrete structure, and a support member is provided to support the rotating shaft of the cutting blade and to be attached to the metal member; The support member is a first member that rotates around the metal member as an axis to cause the cutting blade to pivot along an outer surface of the metal member; a second member for guiding the cutting blade to be pivoted; With the cutting blade in contact with the outer surface of the metal member, the first member rotates, and the cutting blade revolves around the outer periphery of the metal member while being guided by the second member, thereby forming a cutting groove along the outer surface of the metal member. A cutting assist device characterized by:

2. the first member has a support hole through which the rotation shaft is passed, the second member has a guide hole through which the rotation shaft portion is passed, the support hole portion is formed long toward the metal member perpendicular to the rotation shaft portion, and includes a farthest support portion farthest from the metal member and a nearest support portion nearest to the metal member, The guide hole portion extends in a direction in which the cutting blade is turned and is formed in a shape that gradually approaches the metal member, and the guide hole portion has a farthest guide portion that is farthest from the metal member and a nearest guide portion that is nearest to the metal member, In a state where the support member is attached to the metal member, The farthest support portion and the farthest guide portion overlap, or the nearest support portion and the nearest guide portion overlap.

2. The cutting assist device according to claim 1, wherein the cutting assist device is a cutting tool.

3. the first member has a first hole portion formed in a recess that fits into the second member and through which the metal member is passed, the second member has a second hole portion formed in a convex shape that mates with the first member and through which the metal member is passed, The first member and the second member are fitted together so as to be relatively rotatable with the metal member passing through them.

3. The cutting assist device according to claim 1 or 2.

4. an outer surface of the first member and / or an outer surface of the second member having a rotational position identifying means for indicating the degree to which the first member has rotated relative to the second member; 4. The cutting assist device according to claim 3.

5. The outer surface of the first member and the outer surface of the second member are identical polygonal shapes.

5. The cutting assist device according to claim 4.

6. a mating member mated with the support member to restrict relative rotation between the first member and the second member; 3. The cutting assist device according to claim 2.

7. the engagement member has a plurality of restriction holes through which the rotation shaft portion is passed, The distance from the restriction hole portion to the metal member is different for each restriction hole portion.

7. The cutting assist device according to claim 6.

8. The plurality of restriction hole portions include a farthest restriction portion that is farthest from the metal member and a nearest restriction portion that is nearest to the metal member, In a state where the engagement member is engaged with the support member, the farthest restriction portion overlaps with the guide hole portion between the farthest guide portion and the nearest guide portion, or the nearest restriction portion overlaps with the nearest guide portion; 8. The cutting assist device according to claim 7.

9. The metal member is an end of a tendon embedded in the existing concrete structure, a tendon anchor, or an end of a reinforcing bar embedded in the existing concrete structure.

3. The cutting assist device according to claim 1 or 2.

10. A cutting method using the cutting assist device according to claim 8, an attachment step of attaching the first member and the second member to a metal member protruding from an end of the existing concrete structure; a predetermined angle rotation step of rotating the cutting blade, with the rotary shaft portion passed through the support hole portion and the guide hole portion, while the cutting blade is in contact with the outer surface of the metal member, and rotating the first member relative to the second member by a predetermined rotation angle to gradually deepen the cutting groove along the outer surface of the metal member; a full-circumferential rotation step of attaching the fitting member to the first member and the second member and rotating the fitting member once to form the cutting grooves around the entire circumference of the outer surface of the metal member; a removal step of removing the fitting member; The predetermined angle rotation step, the full circumference rotation step, and the removal step are repeated in order until the depth of the cut groove reaches a desired depth. A cutting method characterized by:

Images